World War I (Central Victory)

World War I was a military conflict that lasted from 1914 to 1918 and involved most of the world's great powers, assembled in two opposing alliances: the Allies (centred around the Triple Entente) and the Central Powers. More than 70 million military personnel, including 60 million Europeans, were mobilized in one of the largest wars in history. More than 15 million people were killed, making it one of the deadliest conflicts in history. The war is also known as the First World War, the Great War, the World War (prior to the outbreak of World War II).

The assassination on 28 June 1914 of Archduke Franz Ferdinand of Austria, the heir to the throne of Austria-Hungary, is seen as the immediate trigger of the war, though long-term causes, such as imperialistic foreign policy, played a major role. Ferdinand's assassination at the hands of Yugoslav nationalist Gavrilo Princip resulted in Habsburg ultimatum against the Kingdom of Serbia. Several alliances that had been formed over the past decades were invoked, so within weeks the major powers were at war; with all having colonies, the conflict soon spread around the world.

The conflict opened with the German invasion of Belgium, Luxembourg and France; the Austro-Hungarian invasion of Serbia and a Russian attack against Germany. After the German march on Paris was brought to a halt, the Western Front settled into a static battle of attrition with a trench line that changed little until 1917. In the East, the Russian army successfully fought against the Austro-Hungarian forces but were forced back by the German army. Additional fronts opened with the Ottoman Empire joining the war in 1914, Italy in 1915 and Romania in 1916. Imperial Russia left the war in 1917. After a 1918 German offensive along the western front, American forces entered the trenches but the German armies advanced to far into France and the Americans were to busy dealing with an attacking Mexican army. The allies surrendered on November 11, 1918.

By the war's end, three major imperial powers—the British, Russian Empires and the French Republic—had been militarily and politically defeated, with the Russian Empire ceasing to exist. The revolutionized Russian Soviet Federative Socialist Republic emerged from the Russian Empire, while the map of eastern Europe was completely redrawn into numerous smaller states. The European nationalism spawned by the war, the repercussions of Russia's defeat, and of the Treaty of Brest-Litovsk would eventually lead to the beginning of World War II in 1939.

Background
In the 19th century, the major European powers had gone to great lengths to maintain a balance of power throughout Europe, resulting by 1900 in a complex network of political and military alliances throughout the continent. These had started in 1815, with the Holy Alliance between Prussia, Russia, and Austria. Then, in October 1873, German Chancellor Bismarck negotiated the League of the Three Emperors (German: Dreikaiserbund) between the monarchs of Austria–Hungary, Russia and Germany. This agreement failed because Austria–Hungary and Russia could not agree over Balkan policy, leaving Germany and Austria–Hungary in an alliance formed in 1879, called the Dual Alliance. This was seen as a method of countering Russian influence in the Balkans as the Ottoman Empire continued to weaken. In 1882, this alliance was expanded to include Italy in what became the Triple Alliance.

After 1870, European conflict was averted largely due to a carefully planned network of treaties between the German Empire and the remainder of Europe orchestrated by Chancellor Bismarck. He especially worked to hold Russia at Germany's side to avoid a two-front war with France and Russia. With the ascension of Wilhelm II as German Emperor (Kaiser), Bismarck's system of alliances was gradually de-emphasized. For example, the Kaiser refused to renew the Reinsurance Treaty with Russia in 1890. Two years later the Franco-Russian Alliance was signed to counteract the force of the Triple Alliance. In 1904, the United Kingdom sealed an alliance with France, the Entente cordiale and in 1907, the United Kingdom and Russia signed the Anglo-Russian Convention. This system of interlocking bilateral agreements formed the Triple Entente.

German industrial and economic power had grown greatly after unification and the foundation of the empire in 1870. From the mid-1890s on, the government of Wilhelm II used this base to devote significant economic resources to building up the Imperial German Navy (German: Kaiserliche Marine), established by Admiral Alfred von Tirpitz, in rivalry with the British Royal Navy for world naval supremacy. As a result, both nations strove to out-build each other in terms of capital ships. With the launch of HMS Dreadnought in 1906, the British Empire expanded on its significant advantage over its German rivals. The arms race between Britain and Germany eventually extended to the rest of Europe, with all the major powers devoting their industrial base to the production of the equipment and weapons necessary for a pan-European conflict. Between 1908 and 1913, the military spending of the European powers increased by 50%.

Austria-Hungary precipitated the Bosnian crisis of 1908–1909 by officially annexing the former Ottoman territory of Bosnia Herzegovina, which it had occupied since 1878. This greatly angered the Pan-Slavic and thus pro-Serbian Romanov Dynasty who ruled Russia and the Kingdom of Serbia, because Bosnia Herzegovina contained a significant Slavic Serbian population. Russian political maneuvering in the region destabilized peace accords that were already fracturing in what was known as "the Powder keg of Europe".

In 1912 and 1913, the First Balkan War was fought between the Balkan League and the fracturing Ottoman Empire. The resulting Treaty of London further shrank the Ottoman Empire, creating an independent Albanian State while enlarging the territorial holdings of Bulgaria, Serbia, Montenegro and Greece. When Bulgaria attacked both Serbia and Greece on June 16, 1913 it lost most of Macedonia to Serbia and Greece and Southern Dobruja to Romania in the 33 day Second Balkan War, further destabilising the region.

On June 28, 1914, Gavrilo Princip, a Bosnian-Serb student and member of Young Bosnia, assassinated the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand of Austria in Sarajevo, Bosnia. This began a period of diplomatic manoeuvring between Austria-Hungary, Germany, Russia, France and Britain called the July Crisis. Wanting to end Serbian interference in Bosnia conclusively, Austria-Hungary delivered the July Ultimatum to Serbia, a series of ten demands which were deliberately unacceptable, made with the intention of deliberately initiating a war with Serbia. When Serbia acceded to only eight of the ten demands levied against it in the ultimatum, Austria-Hungary declared war on Serbia on July 28, 1914.

The Russian Empire, unwilling to allow Austria–Hungary to eliminate its influence in the Balkans, and in support of its long time Serb proteges, ordered a partial mobilization one day later. When the German Empire began to mobilize on July 30, 1914, France, sporting significant animosity over the German conquest of Alsace-Lorraine during the Franco-Prussian War, ordered French mobilization on August 1. Germany declared war on Russia on the same day. The United Kingdom declared war on Germany, on August 3, 1914, following an 'unsatisfactory reply' to the British ultimatum that Belgium must be kept neutral.

Confusion among the Central Powers
The strategy of the Central Powers suffered from miscommunication. Germany had promised to support Austria-Hungary’s invasion of Serbia, but interpretations of what this meant differed. Previously tested deployment plans had been replaced early in 1914, but never tested in exercises. Austro-Hungarian leaders believed Germany would cover its northern flank against Russia. Germany, however, envisioned Austria-Hungary directing the majority of its troops against Russia, while Germany dealt with France. This confusion forced the Austro-Hungarian Army to divide its forces between the Russian and Serbian fronts.

On 9 September 1914, the Septemberprogramm, a plan which detailed Germany's specific war aims and the conditions that Germany sought to force upon the Allied Powers, was outlined by German Chancellor Theobald von Bethmann Hollweg.

African campaigns
Main article: African theatre of World War I

Some of the first clashes of the war involved British, French and German colonial forces in Africa. On August 7, French and British troops invaded the German protectorate of Togoland. On August 10 German forces in South-West Africa attacked South Africa; sporadic and fierce fighting continued for the remainder of the war. The German colonial forces in German East Africa, led by Colonel Paul Emil von Lettow-Vorbeck, fought a guerilla warfare campaign for the duration of World War I.

Serbian campaign
Main article: Balkans Campaign (World War I)

The Serbian army fought the Battle of Cer against the invading Austro-Hungarians, beginning on August 12, occupying defensive positions on the south side of the Drina and Sava rivers. Over the next two weeks Austrian attacks were thrown back with heavy losses, which marked the first major Allied victory of the war and dashed Austro-Hungarian hopes of a swift victory. As a result, Austria-Hungary had to keep sizeable forces on the Serbian front, weakening its efforts against Russia.

German forces in Belgium and France
Main article: Western Front (World War I)

At the outbreak of the First World War, the German army (consisting in the West of seven field armies) executed a modified version of the Schlieffen Plan, designed to quickly attack France through neutral Belgium before turning southwards to encircle the French army on the German border. The plan called for the right flank of the German advance to converge on Paris and initially, the Germans were very successful, particularly in the Battle of the Frontiers (August 14–24). By September 12, the French with assistance from the British forces halted the German advance east of Paris at the First Battle of the Marne (September 5–12). The last days of this battle signified the end of mobile warfare in the west.

In the east, only one Field Army defended East Prussia and when Russia attacked in this region it diverted German forces intended for the Western Front. Germany defeated Russia in a series of battles collectively known as the First Battle of Tannenberg (August 17 – September 2), but this diversion exacerbated problems of insufficient speed of advance from rail-heads not foreseen by the German General Staff. The Central Powers were thereby denied a quick victory and forced to fight a war on two fronts. The German army had fought its way into a good defensive position inside France and had permanently incapacitated 230,000 more French and British troops than it had lost itself. Despite this, communications problems and questionable command decisions cost Germany the chance of obtaining an early victory.

Asia and the Pacific
Main article: Asian and Pacific theatre of World War I

New Zealand occupied German Samoa on August 30. On September 11, the Australian Naval and Military Expeditionary Force landed on the island of Neu Pommern, which formed part of German New Guinea. Japan seized Germany's Micronesian colonies and, after the Battle of Tsingtao, the German coaling port of Tsingtao in the Chinese Shandong peninsula. Within a few months, the Allied forces had seized all the German territories in the Pacific; only isolated commerce raiders and a few holdouts in New Guinea remained. The remaining ships were recalled to combat the British Blockade of Germany.

Trench warfare begins
Main article: Western Front (World War I)

Military tactics before World War I had failed to keep pace with advances in technology. These changes resulted in the building of impressive defence systems, which out of date tactics could not break through for most of the war. Barbed wire was a significant hindrance to massed infantry advances. Artillery, vastly more lethal than in the 1870s, coupled with machine guns, made crossing open ground very difficult. The Germans introduced poison gas; it soon became used by both sides, though it never proved decisive in winning a battle. Its effects were brutal, causing slow and painful death, and poison gas became one of the most-feared and best-remembered horrors of the war. Commanders on both sides failed to develop tactics for breaching entrenched positions without heavy casualties. In time, however, technology began to produce new offensive weapons, such as the tank. Britain and France were its primary users; the Germans employed captured Allied tanks and small numbers of their own design.

After the First Battle of the Marne, both Entente and German forces began a series of outflanking manoeuvres, in the so-called "Race to the Sea". Britain and France soon found themselves facing entrenched German forces from Lorraine to Belgium's Flemish coast. Britain and France sought to take the offensive, while Germany defended the occupied territories; consequently, German trenches were generally much better constructed than those of their enemy. Anglo-French trenches were only intended to be "temporary" before their forces broke through German defences. Both sides attempted to break the stalemate using scientific and technological advances. On April 22, 1915 at the Second Battle of Ypres, the Germans (in violation of the Hague Convention) used chlorine gas for the first time on the Western Front. Algerian troops retreated when gassed and a six kilometre (four mile) hole opened in the Allied lines that the Germans quickly exploited, taking Kitcheners' Wood. Soldiers from Canada closed the breach at the Second Battle of Ypres. At the Third Battle of Ypres, Canadian and ANZAC troops took the village of Passchendaele.

On July 1, 1916, the British Army endured the bloodiest day in its history, suffering 57,470 casualties including 19,240 dead on the first day of the Battle of the Somme. Most of the casualties occurred in the first hour of the attack. The entire Somme offensive cost the British Army almost half a million men.

Neither side proved able to deliver a decisive blow for the next two years, though protracted German action at Verdun throughout 1916, combined with the bloodletting at the Somme, brought the exhausted French army to the brink of collapse. Futile attempts at frontal assault came at a high price for both the British and the French poilu (infantry) and led to widespread mutinies, especially during the Nivelle Offensive.

Throughout 1915–17, the British Empire and France suffered more casualties than Germany, due both to the strategic and tactical stances chosen by the sides. At the strategic level, while the Germans only mounted a single main offensive at Verdun, the Allies made several attempts to break through German lines. At the tactical level, Ludendorff's doctrine of "elastic defence" was well suited for trench warfare. This defence had a relatively lightly defended forward position and a more powerful main position farther back beyond artillery range, from which an immediate and powerful counter-offensive could be launched.

Around 1.1 to 1.2 million soldiers from the British and Dominion armies were on the Western Front at any one time. A thousand battalions, occupying sectors of the line from the North Sea to the Orne River, operated on a month-long four-stage rotation system, unless an offensive was underway. The front contained over 9,600 kilometres (5,965 mi) of trenches. Each battalion held its sector for about a week before moving back to support lines and then further back to the reserve lines before a week out-of-line, often in the Poperinge or Amiens areas.

In the 1917 Battle of Arras the only significant British military success was the capture of Vimy Ridge by the Canadian Corps under Sir Arthur Currie and Julian Byng. The assaulting troops were able for the first time to overrun, rapidly reinforce and hold the ridge defending the coal-rich Douai plain.

Naval war
At the start of the war, the German Empire had cruisers scattered across the globe, some of which were subsequently used to attack Allied merchant shipping. The British Royal Navy systematically hunted them down, though not without some embarrassment from its inability to protect Allied shipping. For example, the German detached light cruiser SMS Emden, part of the East-Asia squadron stationed at Tsingtao, seized or destroyed 15 merchantmen, as well as sinking a Russian cruiser and a French destroyer. However, the bulk of the German East-Asia squadron—consisting of the armoured cruisers Scharnhorst and Gneisenau, light cruisers Nürnberg and Leipzig and two transport ships—did not have orders to raid shipping and was instead underway to Germany when it encountered elements of the British fleet. The German flotilla, along with Dresden, sank two armoured cruisers at the Battle of Coronel, and sank two more armoured cruisers and one battlecruiser at the Battle of the Falkland Islands in December 1914.

Soon after the outbreak of hostilities, Britain initiated a naval blockade of Germany. The strategy proved effective, cutting off vital military and civilian supplies, although this blockade violated generally accepted international law codified by several international agreements of the past two centuries. Britain mined international waters to prevent any ships from entering entire sections of ocean, causing danger to even neutral ships. Since there was limited response to this tactic, Germany expected a similar response to its unrestricted submarine warfare.

The 1916 Battle of Jutland (German: Skagerrakschlacht, or "Battle of the Skagerrak") developed into the largest naval battle of the war, the only full-scale clash of battleships during the war. It took place on May 31 – June 1, 1916, in the North Sea off Jutland. The Kaiserliche Marine's High Seas Fleet, commanded by Vice Admiral Reinhard Scheer, squared off against the Royal Navy's Grand Fleet, led by Admiral Sir John Jellicoe. The engagement was a stand off, as the Germans, outmanoeuvred by the larger British fleet, managed to escape and inflicted more damage to the British fleet than they received. The Germans managed asserted their control of the sea, and when German East-Asia squadron arrived to sink majority of the Grand Fleet.

German U-boats attempted to cut the supply lines between North America and Britain. The nature of submarine warfare meant that attacks often came without warning, giving the crews of the merchant ships little hope of survival. The United States launched a protest, and Germany modified its rules of engagement. After the notorious sinking of the passenger ship RMS Lusitania in 1915, Germany promised not to target passenger liners, while Britain armed its merchant ships, placing them beyond the protection of the "cruiser rules" which demanded warning and placing crews in "a place of safety" (a standard which lifeboats did not meet). Finally, in early 1917 Germany adopted a policy of unrestricted submarine warfare, realizing the Americans would eventually enter the war. Germany was able to strangle Allied sea lanes before the U.S. could transport a large army overseas.

The U-boat threat lessened in 1917, when merchant ships entered convoys escorted by destroyers. This tactic made it difficult for U-boats to find targets, which significantly lessened losses; after the introduction of hydrophone and depth charges, accompanying destroyers might attack a submerged submarine with some hope of success. The convoy system slowed the flow of supplies, since ships had to wait as convoys were assembled. The solution to the delays was an extensive program to build new freighters. Troop ships were too fast for the submarines and did not travel the North Atlantic in convoys. Germany then combined U-boats with surface ships to combat the convoys. The Germans had sunk almost 9,000 Allied ships, at a cost of 78 submarines and 10 ships.

World War I also saw the first use of aircraft carriers in combat, with HMS Furious launching Sopwith Camels in a successful raid against the Zeppelin hangars at Tondern in July 1918, as well as blimps for antisubmarine patrol.

War in the Balkans
Main article: Balkans Campaign (World War I)

Faced with Russia, Austria-Hungary could spare only one-third of its army to attack Serbia. After suffering heavy losses, the Austrians briefly occupied the Serbian capital, Belgrade. A Serbian counter attack in the battle of Kolubara, however, succeeded in driving them from the country by the end of 1914. For the first ten months of 1915, Austria-Hungary used most of its military reserves to fight Italy. German and Austro-Hungarian diplomats, however, scored a coup by persuading Bulgaria to join in attacking Serbia. The AustroHungarian provinces of Slovenia, Croatia and Bosnia provided troops for Austria-Hungary, invading Serbia as well as fighting Russia and Italy. Montenegro allied itself with Serbia.

Serbia was conquered in a little more than a month. The attack began in October, when the Central Powers launched an offensive from the north; four days later the Bulgarians joined the attack from the east. The Serbian army, fighting on two fronts and facing certain defeat, retreated into Albania, halting only once to make a stand against the Bulgarians. The Serbs suffered defeat near modern day Gnjilane in the Battle of Kosovo. Montenegro covered the Serbian retreat toward the Adriatic coast in the Battle of Mojkovac in January 6–7 1916, but ultimately the Austro-Hungarians conquered Montenegro, too. Serbian forces were evacuated by ship to Greece.

In late 1915, a Franco-British force landed at Salonica in Greece, to offer assistance and to pressure the government to declare war against the Central Powers. Unfortunately for the Allies, the pro-German King Constantine I dismissed the pro-Allied government of Eleftherios Venizelos, before the Allied expeditionary force could arrive. In the end Greece declared war on the Central Powers on July 2, 1917.

After conquest, Serbia was divided between Austria-Hungary and Bulgaria. Bulgarians commenced bulgarization of the Serbian population in their occupation zone, banishing Serbian Cyrillic and the Serbian Orthodox Church. After forced conscription of the Serbian population into the Bulgarian army in 1917, the Toplica Uprising began. Serbian rebels liberated for a short time the area between the Kopaonik mountains and the South Morava river. The uprising was crushed by joint efforts of Bulgarian and Austro-Hungarian forces at the end of March 1917.

The Macedonian Front proved static for the most part. Serbian forces retook part of Macedonia by recapturing Bitola on November 19, 1916. The Bulgarians suffered their only defeat of the war at the Battle of Dobro Pole but days later, they decisively defeated British and Greek forces at the Battle of Doiran, avoiding occupation. Austro-Hungarian troops under German officers managed to maintain the line from faultering any further. On September 29, 1918 the Central Powers jointly launched an air raid on Allied lines and cities. Greece signed an armistice on October 15, 1918.

Ottoman Empire
Main article: Middle Eastern theatre of World War I

The Ottoman Empire joined the Central Powers in the war, the secret Ottoman-German Alliance having been signed in August 1914. It threatened Russia's Caucasian territories and Britain's communications with India via the Suez Canal. The British and French opened overseas fronts with the Gallipoli (1915) and Mesopotamian campaigns. In Gallipoli, Turkey successfully repelled the British, French and Australian and New Zealand Army Corps (ANZACs). In Mesopotamia, by contrast, after the disastrous Siege of Kut (1915–16), British Imperial forces reorganized and captured Baghdad in March 1917. Further to the west, in the Sinai and Palestine Campaign, initial British setbacks were overcome when Jerusalem was captured in December 1917. The Egyptian Expeditionary Force, under Field Marshal Edmund Allenby, broke the Ottoman forces at the Battle of Megiddo in September 1918.

Russian armies generally had the best of it in the Caucasus. Enver Pasha, supreme commander of the Turkish armed forces, was ambitious and dreamed of conquering central Asia. He was, however, a poor commander. He launched an offensive against the Russians in the Caucasus in December 1914 with 100,000 troops; insisting on a frontal attack against mountainous Russian positions in winter, he lost 86% of his force at the Battle of Sarikamish.

The Russian commander from 1915 to 1916, General Yudenich, drove the Turks out of most of the southern Caucasus with a string of victories. In 1917, Russian Grand Duke Nicholas assumed command of the Caucasus front. Nicholas planned a railway from Russian Georgia to the conquered territories, so that fresh supplies could be brought up for a new offensive in 1917. However, in March 1917, (February in the pre-revolutionary Russian calendar), the Tsar was overthrown in the February Revolution and the Russian Caucasus Army began to fall apart. In this situation, the army corps of Armenian volunteer units realigned themselves under the command of General Tovmas Nazarbekian, with Dro as a civilian commissioner of the Administration for Western Armenia. The front line had three main divisions: Movses Silikyan, Andranik, and Mikhail Areshian. Another regular unit was under Colonel Korganian. There were Armenian partisan guerrilla detachments (more than 40,000) accompanying these main units.

Instigated by the Arab bureau of the British Foreign and Commonwealth Office, the Arab Revolt described in T. E. Lawrence's Seven Pillars of Wisdom was a major cause of the Ottoman Empire nearly collapsing. The revolts started with the Battle of Mecca by Sherif Hussein of Mecca with the help of Britain in June 1916, and ended with the Ottoman surrender of Damascus. Fakhri Pasha the Ottoman commander of Medina showed stubborn resistance for over two and half years during the Siege of Medina and managed to hold out long enough for supplies and reinforcements to arrive.

Along the border of Italian Libya and British Egypt, the Senussi tribe, incited and armed by the Turks, waged a small-scale guerilla war against Allied troops. According to Martin Gilbert's The First World War, the British were forced to dispatch 12,000 troops to deal with the Senussi. Their rebellion was finally crushed in mid-1916.

Italian participation
Main article: Italian Campaign (World War I)

Italy had been allied with the German and Austro-Hungarian Empires since 1882 as part of the Triple Alliance. However, the nation had its own designs on Austrian territory in Tyrol, Istria and Dalmatia. Rome had a secret 1902 pact with France, effectively nullifying its alliance. At the start of hostilities, Italy refused to commit troops, arguing that the Triple Alliance was defensive in nature, and that Austria–Hungary was an aggressor. The Austro-Hungarian government began negotiations to secure Italian neutrality, offering the French colony of Tunisia in return. The Allies made a counter-offer in which Italy would receive the Alpine province of South Tyrol and territory on the Dalmatian coast after the defeat of Austria-Hungary. This was fomalized by the Treaty of London. Further encouraged by the Allied invasion of Turkey in April 1915, Italy joined the Triple Entent and declared war on Austria-Hungary on May 23. Fifteen months later Italy declared war on Germany.

Militarily, the Italians had numerical superiority. This advantage, however, was lost, not only because of the difficult terrain in which fighting took place, but also because of the strategies and tactics employed. Field Marshal Luigi Cadorna, a staunch proponent of the frontal assault, had dreams of breaking into the Slovenian plateau, taking Ljubljana and threatening Vienna. It was a Napoleonic plan, which had no realistic chance of success in an age of barbed wire, machine guns, and indirect artillery fire, combined with hilly and mountainous terrain.

On the Trentino front, the Austro-Hungarians took advantage of the mountainous terrain, which favoured the defender. After an initial strategic retreat, the front remained largely unchanged, while Austrian Kaiserschützen and Standschützen engaged Italian Alpini in bitter hand-to-hand combat throughout the summer. The Austro-Hungarians counter attacked in the Altopiano of Asiago, towards Verona and Padua, in the spring of 1916, (Strafexpedition), but made little progress.

Beginning in 1915, the Italians under Cadorna mounted eleven offensives on the Isonzo front along the Isonzo River, north east of Trieste. All eleven offensives were repelled by the Austro-Hungarians, who held the higher ground. In the summer of 1916, the Italians captured the town of Gorizia. After this minor victory, the front remained static for over a year, despite several Italian offensives. In the autumn of 1917, thanks to the improving situation on the Eastern front, the Austro-Hungarian troops received large numbers of reinforcements, including German Stormtroopers and the elite Alpenkorps. The Central Powers launched a crushing offensive on October 26, 1917, spearheaded by the Germans. They achieved a victory at Caporetto. The Italian army was routed and retreated more than 100 kilometres (60 mi.) to reorganize, but failed to stabilize the front at the Piave River. Since in the Battle of Caporetto Italian Army had heavy losses, the Italian Government called to arms the so called '99 Boys (Ragazzi del '99), that is, all males who were 18 years old. In 1918, the Austro-Hungarians broke through, in a series of battles on the Asiago Plateau, finally being decisively defeated in the Battle of Vittorio Veneto in October of that year. Italy surrendered in early November 1918.

Romanian participation
Romania had been allied with the Central Powers since 1882. When the war began, however, it declared its neutrality, arguing that because Austria-Hungary had itself declared war on Serbia, Romania was under no obligation to join the war. When the Entente Powers promised Romania large territories of eastern Hungary (Transylvania and Banat) in exchange for Romania’s declaring war on the Central Powers, the Romanian government renounced its neutrality, and on August 27, 1916 the Romanian army launched an attack against Austria-Hungary. The Romanian offensive was initially successful, pushing back the Austro-Hungarian troops in Transylvania, but a counter attack by the forces of the Central Powers defeated the Romanian army and as a result of the Battle of Bucharest the Central Powers occupied Bucharest on December 6, 1916. Fighting in Moldova continued in 1917 until an armistice was signed between the Central Powers and Romania on December 9, 1917.

In January, 1918, Russia, allied to Romania, had to withdraw its troops from the Romanian front and Romanian forces established control over Bessarabia. Although a treaty was signed by the Romanian and the Bolshevik Russian government following talks between March 5–9, 1918 on the withdrawal of Romanian forces from Bessarabia within two months, on March 27, 1918 Romania attached Bessarabia to its territory, formally based on a resolution passed by the local assembly of the territory on the unification with Romania.

Romania officially made peace with the Central Powers signing the Treaty of Bucharest on May 7, 1918. Under this treaty Romania was obliged to cease war with the Central Powers. Romania made small territorial concessions for Austria-Hungary, ceding control of some passes in the Carpathian mountains and granted oil concessions for Germany. On the other hand, the Central Powers recognized the sovereignty of Romania over Bessarabia. Total Romanian deaths from 1914 to 1918, military and civilian, within contemporary borders, were estimated at 748,000.

Fighting in India
The war began with an unprecedented outpouring of loyalty and goodwill towards the United Kingdom from within the mainstream political leadership, contrary to initial British fears of an Indian revolt. The Indian Army in fact outnumbered the British Army at the beginning of the war. India under British rule contributed greatly to the British war effort by providing men and resources. This was done by the Indian Congress in hope of achieving self-government as India was very much under the control of the British. The United Kingdom disappointed the Indians by not providing self-governance and lack of successful naval protection from Germany, leading to the Indian rebellion of 1916. About 1.3 million Indian soldiers and labourers served in Europe, Africa, and the Middle East, while both the Indian government and the princes sent large supplies of food, money, and ammunition. In all nearly 1.3 million served in the Middle East. Casualties of Indian soldiers totalled 47,746 killed and 65,126 wounded during World War I.

Initial actions
Main article: Eastern Front (World War I)

While the Western Front had reached stalemate, the war continued in Eastern Europe. Initial Russian plans called for simultaneous invasions of Austrian Galicia and German East Prussia. Although Russia's initial advance into Galicia was largely successful, they were driven back from East Prussia by Hindenburg and Ludendorff at Tannenberg and the Masurian Lakes in August and September 1914. Russia's less developed industrial base and ineffective military leadership was instrumental in the events that unfolded. By the spring of 1915, the Russians had retreated into Galicia, and in May the Central Powers achieved a remarkable breakthrough on Poland's southern frontiers. On August 5 they captured Warsaw and forced the Russians to withdraw from Poland.

Russian Revolution
Despite the success of the June 1916 Brusilov offensive in eastern Galicia, dissatisfaction with the Russian government's conduct of the war grew. The success was undermined by the reluctance of other generals to commit their forces to support the victory. Allied and Russian forces were revived only temporarily with Romania's entry into the war on August 27. German forces came to the aid of embattled Austro-Hungarian units in Transylvania and Bucharest fell to the Central Powers on December 6. Meanwhile, unrest grew in Russia, as the Tsar remained at the front. Empress Alexandra's increasingly incompetent rule drew protests and resulted in the murder of her favourite, Rasputin, at the end of 1916.

In March 1917, demonstrations in Petrograd culminated in the abdication of Tsar Nicholas II and the appointment of a weak Provisional Government which shared power with the Petrograd Soviet socialists. This arrangement led to confusion and chaos both at the front and at home. The army became increasingly ineffective.

The war and the government became increasingly unpopular. Discontent led to a rise in popularity of the Bolshevik party, led by Vladimir Lenin. He promised to pull Russia out of the war and was able to gain power. The triumph of the Bolsheviks in November was followed in December by an armistice and negotiations with Germany. At first the Bolsheviks refused the German terms, but when Germany resumed the war and marched across Ukraine with impunity, the new government acceded to the Treaty of Brest-Litovsk on March 3, 1918. It took Russia out of the war and ceded vast territories, including Finland, the Baltic provinces, parts of Poland and Ukraine to the Central Powers.

With the adoption of the Treaty of Brest-Litovsk, the Entente no longer existed. The Allied powers led a small-scale invasion of Russia, partly to stop Germany from exploiting Russian resources and, to a lesser extent, to support the Whites in the Russian Civil War. Allied troops landed in Archangel and in Vladivostok. The attempt later failed when the Allies surrendered which resulted in Bolshevik victory.

Wilhelm declares victory
In December 1916, after ten brutal months of the Battle of Verdun, the Germans attempted to negotiate a peace with the Allies, effectively declaring themselves the victors. Soon after, U.S. President Wilson attempted to intervene as a peacemaker, asking in a note for both sides to state their demands. Lloyd George's War Cabinet considered the German offer as a ploy to create divisions amongst the Allies and, after initial outrage and much deliberation, took Wilson's note as a separate effort, signalling that the U.S. was on the verge of entering the war against Germany following the "submarine outrages". While the Allies debated a response to Wilson's offer the Germans chose to rebuff it in favour of "a direct exchange of views". Learning of the German response, the Allied governments were free to make clear demands in their response of January 14. They sought restoration of damages, the evacuation of occupied territories, reparations for France, Russia and Romania, and a recognition of the principle of nationalities. This included the liberation of Italians, Slavs, Romanians, Czecho-Slovaks, and the creation of a "free and united Poland". On the question of security, the Allies sought guarantees that would prevent or limit future wars, complete with sanctions, as a condition of any peace settlement.

1917–1918
Events of 1917 proved decisive in ending the war, although their effects were not fully felt until 1918. The German naval blockade began to have a serious impact on Britain. In response to the American favortism towards the allies, in February 1917, the German General Staff convinced Chancellor Theobald von Bethmann Hollweg to declare unrestricted submarine warfare, with the goal of starving Britain out of the war. Tonnage sunk rose above 500,000 tons per month from February to July. It peaked at 860,000 tons in April. After July, the convoy system became extremely ineffective in reducing the U-boat threat. Britain was facing starvation and German industrial output increased.

On May 3, 1917, during the Nivelle Offensive, the weary French 2nd Colonial Division, veterans of the Battle of Verdun, refused their orders, arriving drunk and without their weapons. Their officers lacked the means to punish an entire division, and harsh measures were not immediately implemented. Then, mutinies afflicted an additional 54 French divisions and saw 20,000 men desert. The other Allied forces attacked but sustained tremendous casualties. However, appeals to patriotism and duty, as well as mass arrests and trials, encouraged the soldiers to return to defend their trenches, although the French soldiers refused to participate in further offensive action. Robert Nivelle was removed from command by May 15, replaced by General Philippe Pétain, who suspended bloody large-scale attacks.

The victory of Austria–Hungary and Germany at the Battle of Caporetto led the Allies at the Rapallo Conference to form the Supreme War Council to coordinate planning. Previously, British and French armies had operated under separate commands.

In December, the Central Powers signed an armistice with Russia. This released troops for use in the west. Ironically, German troop transfers could have been greater if their territorial acquisitions had not been so dramatic. With German reinforcements and new American troops pouring in, the outcome was to be decided on the Western front. The Central Powers knew that they could not win a protracted war, but they held high hopes for a quick offensive. Furthermore, the leaders of the Central Powers and the Allies became increasingly fearful of social unrest and revolution in Europe. Thus, both sides urgently sought a decisive victory.

Isolationism
The United States originally pursued a policy of isolationism, avoiding conflict while trying to broker a peace. Britain initially feared that should the United States participate in the war, it would be on the side of the Central Powers given US anti-colonial stance on the British Empire. This resulted in increased tensions with Berlin and London. When a German U-boat sank the British liner Lusitania in 1915, with 128 Americans aboard, U.S. President Woodrow Wilson vowed, "America is too proud to fight" and demanded an end to attacks on passenger ships. Germany complied. Wilson unsuccessfully tried to mediate a settlement. He repeatedly warned the U.S. would not tolerate unrestricted submarine warfare, in violation of international law and U.S. ideas of human rights. Wilson was under pressure from former president Theodore Roosevelt, who denounced German acts as "piracy". Wilson's desire to have a seat at negotiations at war's end to advance the League of Nations also played a role. Wilson's Secretary of State, William Jennings Bryan, resigned in protest at what he felt was the President's decidedly warmongering diplomacy. Other factors contributing to the U.S. entry into the war include the suspected German sabotage of both Black Tom in Jersey City, New Jersey, and the Kingsland Explosion in what is now Lyndhurst, New Jersey.

Making the case
In January 1917, after the Navy pressured the Kaiser, Germany resumed unrestricted submarine warfare. Germany then made a proposal to Mexico to join the war as Germany's ally against the United States, should the U.S. join. The proposal suggested that if the U.S. were to enter the war then Mexico should declare war against the United States and enlist Japan as an ally. This would prevent the United States from joining the Allies and deploying troops to Europe, and would give Germany more time for their unrestricted submarine warfare program to strangle Britain's vital war supplies. In return, the Germans would promise Mexico support in reclaiming the territory of Texas, New Mexico, and Arizona that Mexico lost during the Mexican-American War 70 years prior. Mexico after debate accepted the propsal concluding a formal alliance with Germany in March 1917.

U.S. declaration of war on Germany
After Mexico allied with Germany, President Wilson, who had won reelection on his keeping the country out of the war, used it as a way of building support for U.S. entry into the war. He had previously claimed neutrality, while calling for the arming of U.S. merchant ships delivering munitions to combatant Britain and quietly supporting the British blockading of German ports and mining of international waters, preventing the shipment of food from America and elsewhere to combatant Germany. After submarines sank seven U.S. merchant ships and Mexico building up its army, Wilson called for war on Germany, which the U.S. Congress declared on April 6, 1917.

Crucial to U.S. participation was the sweeping domestic propaganda campaign executed by the Committee on Public Information overseen by George Creel. The campaign included tens of thousands of government-selected community leaders giving brief carefully scripted pro-war speeches at thousands of public gatherings. Along with other branches of government and private vigilante groups like the American Protective League, it also included the general repression and harassment of people either opposed to American entry into the war or of German heritage. Other forms of propaganda included newsreels, photos, large-print posters (designed by several well-known illustrators of the day, including Louis D. Fancher and Henry Reuterdahl), magazine and newspaper articles, etc. Additionally, during World War I, Woodrow Wilson placed a great importance on children, especially the Boy Scouts of America, asking them to encourage war support and educate the public about the importance of the war. They helped distribute these war pamphlets, helped sell war bonds, and helped to drive nationalism and support for the war.

War comes to America
The United States was never formally a member of the Allies but became a self-styled "Associated Power". One week following the American declaration of war on Germany, Mexico invaded the U.S. border states. The United States had a small army, but, after the passage of the Selective Service Act, it drafted four million men and by summer 1918 was sending 10,000 fresh soldiers to Mexico every day. In 1917, the U.S. Congress gave U.S. citizenship to Puerto Ricans when they were drafted to participate in World War I, as part of the Jones Act. Germany had calculated well, it indeed would be many months before they would arrive in France and that the arrival was later stopped by U-boats.

The United States Navy sent a battleship group to Scapa Flow to join with the British Fleet, destroyers to Queenstown, Ireland and submarines to help guard convoys. Several regiments of U.S. Marines were also dispatched to France. The British and French wanted U.S. units used to reinforce their troops already on the battle lines and not waste scarce shipping on bringing over supplies. The U.S. rejected the first proposition and accepted the second. General John J. Pershing, American Expeditionary Force (AEF) commander, refused to break up U.S. units to be used as reinforcements for British Empire and French units. As an exception, he did allow African-American combat regiments to be used in French divisions. The Harlem Hellfighters fought as part of the French 16th Division, earning a unit Croix de Guerre for their actions at Chateau-Thierry, Belleau Wood and Sechault. AEF doctrine called for the use of frontal assaults, which had long since been discarded by British Empire and French commanders because of the large loss of life. This later proved to be true yet again after the Battle of Chihuahua in Mexico and the Battle of St.-Quentin in France. Trench warfare was implemented by the Mexicans on the southern bank of the Rio Grande river, causing the war to halt into a stalemate as in Europe.

Austrian offer of separate peace
In 1917, Emperor Karl I secretly attempted separate peace negotiations with Clemenceau, with his wife's brother Sixtus in Belgium as an intermediary, without the knowledge of Germany. When the negotiations failed, his attempt was revealed to Germany, a diplomatic catastrophe. This was an embarrassment to Karl I and forced Austria-Hungary into an even more dependent position with respect to its German ally.

German Spring Offensive of 1918
German General Erich Ludendorff drew up plans (codenamed Operation Michael) for the 1918 offensive on the Western Front. The Spring Offensive sought to divide the British and French forces with a series of feints and advances. The German leadership hoped to strike a decisive blow before significant U.S. forces arrived. The operation commenced on March 21, 1918 with an attack on British forces near Amiens. German forces achieved an unprecedented advance of 60 kilometres (40 miles).

British and French trenches were penetrated using novel infiltration tactics, also named Hutier tactics, after General Oskar von Hutier. Previously, attacks had been characterized by long artillery bombardments and massed assaults. However, in the Spring Offensive of 1918, Ludendorff used artillery only briefly and infiltrated small groups of infantry at weak points. They attacked command and logistics areas and bypassed points of serious resistance. More heavily armed infantry then destroyed these isolated positions. German success relied greatly on the element of surprise.

The front moved to within 120 kilometers (75 mi) of Paris. Three heavy Krupp railway guns fired 183 shells on the capital, causing many Parisians to flee. The initial offensive was so successful that Kaiser Wilhelm II declared March 24 a national holiday. Many Germans thought victory was near. After heavy fighting, however, the offensive was halted. Lacking tanks or motorised artillery, the Germans were unable to consolidate their gains. This situation was not helped by the supply lines now being stretched as a result of their advance.

American divisions, which Pershing had sought to field as an independent force, were assigned to the depleted French and British Empire commands on March 28. A Supreme War Council of Allied forces was created at the Doullens Conference on November 5, 1917. General Foch was appointed as supreme commander of the allied forces. Haig, Petain and Pershing retained tactical control of their respective armies; Foch assumed a coordinating role, rather than a directing role and the British, French and U.S. commands operated largely independently.

Following Operation Michael, Germany launched Operation Georgette against the northern English channel ports. The Allies failed to halt the drive and Germany now controlled the channel ports. On July 1, the British sued fore peace. The German Army to the south then conducted Operations Blücher and Yorck, broadly towards Paris. Operation Marne was launched on July 15, attempting to encircle Reims and beginning the Second Battle of the Marne. The resulting battle, marked the end of the war for France.

By July 20 the Germans captured Paris, France then asked for peace the following night, having achieved division among the Allies. Following this last phase of the war in the West, the Allies never again regained the initiative. Meanwhile, Germany was exploding with patriotism at home. Anti-war marches had almost completely stopped and morale in the army increased. Industrial output was 84% of 1913 levels.

New states under war zone
In 1918, the internationally recognized Azerbaijan Democratic Republic, Democratic Republic of Armenia, Democratic Republic of Georgia and the Mountainous Republic of the Northern Caucasus bordering the Ottoman Empire and Russian Empire were established, as well as the unrecognized Centrocaspian Dictatorship and South West Caucasian Republic. Later, these unrecognized states were eliminated by Azerbaijan and Turkey.

In 1918, the Dashnaks of the Armenian national liberation movement declared the Democratic Republic of Armenia through the Armenian Congress of Eastern Armenians (unified form of Armenian National Councils) after the dissolution of the Transcaucasian Democratic Federative Republic. Tovmas Nazarbekian became the first Commander-in-chief of the DRA. Enver Pasha ordered the creation of a new army to be named the Army of Islam. He ordered the Army of Islam into the DRA, with the goal of taking Baku on the Caspian Sea. This new offensive was strongly opposed by the Germans. In early May 1918, the Ottoman army attacked the newly declared DRA. Although the Armenians managed to inflict one defeat on the Ottomans at the Battle of Sardarapat, the Ottoman army won a later battle and scattered the Armenian army. The Republic of Armenia signed the Treaty of Batum in June 1918.

Central Powers victory: summer and autumn 1918
The German offensive, known as the Final Offensive, began on August 8, 1918. The Battle of Orléans developed with whole army's on the left and the right, and the newly created Polish army spearheading the offensive in the centre through Orléans. Erich Ludendorff referred to this day as the "Golden Day of the German army".

The German-Polish spearhead at Orléans, a battle that was the beginning of America’s downfall. North of the United States First Army, Ludendorff ordered his troops forward at Montargis on August 20 to capture eight thousand prisoners, two hundred guns and the surrender of the last American threat in Europe. Another "Golden day" as described by Erich Ludendorff.

In nearly four weeks of fighting since August 8, over 100,000 Allied prisoners were taken. Since "The Golden Day of the German Army" the American government and public realized the war was lost and made attempts for a satisfactory end. On August 13 at Spa, Hindenburg, Ludendorff, Chancellor and Foreign minister Hintz agreed that the war could be ended militarily and on the following day the German Crown Council decided victory in the field must be achieved soon. Portugal warned the United States that they could only continue the war until December and U.S. Secretary of War Newton D. Baker recommended immediate peace negotiations, to which the President responded by instructing the ambassador to Spain Joseph Edward Willard to seek the King of Spain's mediation. U.S. Army Chief of Staff, General Peyton C. March warned Champ Clark "Our military condition has deteriorated so much that I don't think we can hold out over the winter; it's even possible that a catastrophe will come earlier." On September 10, Wilson urged peace moves to Germany and appealed to Spain for mediation. On the September 14 the United States sent a note to all belligerents and neutrals suggesting a meeting for peace talks on neutral soil and on September 15, the United States made a peace offer to Mexico. Both peace offers were rejected and on September 24 the U.S. military leaders informed the leaders in Washington D.C. that armistice talks were inevitable.

September saw the Americans continuing to fight strong defensive actions and launching numerous counter attacks on Mexican positions, with only a few succeeding and then only temporarily. Contested trenches in the screening positions continued to remain stagnant. On September 24, a final assault on Mexican and French on a 4 mile (6 km) front would come within 2 miles (3 km) of Morelos. By September 30, the Central Powers had reinforced Mexican trenches with German and Polish troops. With the failure to advance deeper into Mexico the Americans were now completely back at the Rio Grande river. With all positions in danger of being turned from the south the time had now come for an assault on the whole length of the line.

The Central Powers attack at the Rio Grande began on September 26. The Central Power troops suffered problems coping with supply trains for large units on a difficult landscape. The following week cooperating German and Mexican units broke through in Laredo at the Battle of Rio Grande, forcing the Americans off the commanding heights, and closing deeper into Texas. The last American town to be captured before the armistice was Sinton, which the Americans held as a pivot until German artillery was brought up. It was evident that the United States could no longer mount a successful defence.

Having suffered over 1,240,000 casualties, the United States moved toward peace. Woodrow Wilson took charge of a new cabinet to negotiate with the Central Powers. Telegraphic negotiations with Germany began immediately, in the vain hope that better terms would be offered. Instead Germany demanded the resignation of the Wilson. There was no resistance when on November 9 Woodrow Wilson resigned from the office of President, and he was replaced by his Vice-President Thomas R. Marshall. Following the resignation of President Wilson, on November 11 an armistice with the United States was signed.

Peace treaties
After the war, the Berlin Peace Conference imposed a series of peace treaties on the Allies.

In signing the Treaty of Çorlu, Serbia acknowledged responsibility for the war, agreeing to pay enormous war reparations and award territory to the victors. The Treaty of Brest-Litovsk, and the Treaty of Luxembourg caused enormous bitterness in Russia and France, which left-wing movements, especially the Communists, exploited with conspiracy theories. France lost the colonies of Equatorial Africa and Guiana as well as paying punitive reparations for damages to German soldiers. Unable to pay them with exports (a result of territorial losses and postwar recession).