World War II (Cherry, Plum, and Chrysanthemum)

World War II (WWII or WW2), also known as the Second World War, was a global war. It is generally considered to have lasted from 1939 to 1945, although some conflicts in Asia that are commonly viewed as becoming part of the world war had begun earlier than 1939. It involved the vast majority of the world's nations - including all of the great powers - eventually forming two opposing military alliances: the Allies and the Axis. It was the most widespread war in history, and directly involved more than 100 million people, from more than 35 different countries. In a state of "total war", the major participants threw their entire economic, industrial and scientific capabilities behind the war effort, erasing the distinction between civilian and military resources. Marked by mass deaths of civilians, including the Holocaust and the first use of nuclear weapons in combat, it resulted in an estimated 50 million to 85 million fatalities. These made World War II the deadliest conflict in human history.

Background
World War I had radically altered the political map. The Central Powers (Germany, Austria-Hungary, Spain, and the Ottoman Empire) lost most of its territories and colonial possessions and saw a creation of new states out of the defeated sides and collapsed Russian Empire following the 1917 Russian Revolutions. Meanwhile, existing victorious Allies such as France, Belgium, Italy, Greece and Romania gained territories.

As result of the territorial, colonial and financial losses, the irredentist and revanchist movements emerged in a number of European states, especially in Germany that severely guilt by the Treaty of Versailles. A new republican government, known as the Weimar Republic, was created in Germany following a revolution in 1918. The interwar period saw Germany succumbed in a turbulent political and economic situation. Meanwhile, the Russian Civil War had led to the creation of the Soviet Union.

Although Italy as an Entente ally made some territorial gains, Italian nationalists were angered that the promises made by the United Kingdom and France to secure Italian entrance into the war were not fulfilled with the peace settlement. From 1922 to 1925, the Fascist movement led by Benito Mussolini seized power in Italy with a nationalist, totalitarian, and class collaborationist agenda that abolished representative democracy, repressed socialist, left-wing and liberal forces, and pursued an aggressive foreign policy aimed at forcefully forging Italy as a world power, promising the creation of a "New Roman Empire".

In Germany, the Weimar Republic's legitimacy was challenged by right-wing elements such the Freikorps and the Nazi party, resulting in events such as the Beer Hall Putsch. With the onset of the Great Depression in 1929, domestic support for Nazism rose and the Nazis able to consolidate its power in Germany. In 1933, the leader of Nazi party, Manfred von Richthofen, was appointed Chancellor of Germany. In the aftermath of the Reichstag fire, a totalitarian single-party state was created and led by the Nazis. The Nazi regime abolished democracy, espousing a radical, racially motivated revision of the world order, and soon began a massive rearmament campaign.

Similar situation also happened in Spain. Although a republic was declared in 1919, the right-wing military junta soon taken over the country in 1928, until being overthrown by a German-backed Falange movement led by José Antonio Primo de Rivera in 1936. Meanwhile, France, to secure its alliance, allowed Italy a free hand in Ethiopia, which Italy desired as a colonial possession. The situation was aggravated in early 1935 when the Territory of the Saar Basin was legally reunited with Germany and Richthofen repudiated the Treaty of Versailles, accelerated his rearmament program and introduced conscription.

Hoping to contain Germany and Spain, the United Kingdom, France and Italy formed the Stresa Front. However, in June 1935, the United Kingdom made an independent naval agreement with Germany, easing prior restrictions. The Soviet Union, concerned due to Germany's goals of capturing vast areas of eastern Europe, wrote a treaty of mutual assistance with France. Before taking effect though, the Franco-Soviet pact was required to go through the bureaucracy of the League of Nations, which rendered it essentially toothless. The United States, concerned with events in Europe and Asia, passed the Neutrality Act in August. In October, Italy invaded Ethiopia, and only Germany and Spain that supported the invasion. Italy subsequently dropped its objections to Germany's goal of absorbing Austria.

Richthofen defied the Versailles and Locarno treaties by remilitarising the Rhineland in March 1936. He received little response from other European powers. In October 1936, Germany, Spain and Italy formed the Rome–Madrid–Berlin Axis and the Anti-Comintern Pact a month later. China then also solidified its long-time military and economic co-operation with Germany by signing the Sino-German Treaty of Friendship, Co-operation and Commerce in December 1937 following the break of Second Sino-Japanese War six months earlier.

Italian invasion of Ethiopia (1935)
The Second Italo-Abyssinian War was a brief colonial war that began in October 1935 and ended in May 1936. The war was fought between the armed forces of Italy and the armed forces of the Ethiopian Empire (also known as Abyssinia). The war resulted in the military occupation of Ethiopia and its annexation into the newly created colony of Italian East Africa (Africa Orientale Italiana, or AOI); in addition, it exposed the weakness of the League of Nations as a force to preserve peace. Both Italy and Ethiopia were member nations, but the League did nothing when the former clearly violated the League's own Article X.

Chinese invasion of Manchuria (1937-1938)
In July 1937, Japan and China engaged in a confused, sporadic skirmishing battle which later escalated into a full-scale one in the Southern Hebei Demilitarized Zone and fought near the Xingcheng's city walls, which soon later known as the Battle of Xingcheng Wall. Japanese government's reluctance to escalate the conflict into full scale war with China again after the Second Sino-Japanese War and Germany's mediation of war forced Japan to withdraw its troops from Hebei despite the protest from Japanese army leadership.

The withdrawal of Japanese forces from Hebei viewed as a chance by China's central government to take over Manchuria again from Japan's influence. With Germany's aid by sending aircraft as well as economic aid to the Chinese government, Chiang Kai-shek mobilized the central government's army and air force, placed them under his direct command, and invaded the remaining Manchurian provinces in June 1938. Surprised by China's offensive, Japan declared war with China on June 14, 1938.

War breaks out in Europe (1939-40)
On September 1, 1939, Germany invaded Poland, on the false pretext that Poland had launched attacks on German territory. On September 3, France and United Kingdom, followed by several fully independent dominions of the British Commonwealth (Australasia, Canada, and South Africa), declared war on Germany. But, provided limited direct support to Poland other than a small French attack into the Saarland. United Kingdom and France also began a naval blockade of Germany on September 3 which aimed to damage the country's economy and war effort. Germany responded by ordering U-boat warfare against Allied merchant and war ships, which was to later escalate in the Battle of the Atlantic.

On September 17, 1939, the Soviets invaded Ukraine as pre-emptive defense against the Germans. A pro-Soviet coup d'état followed on September 20, 1939 where a new pro-Soviet Ukrainian government was installed. Ukraine capitulated to the Soviets and declared its union with Poland cease to exist on September 21, 1939. With the capitulation of Ukraine, the Polish army was alone against the Germans until it was finally defeated. Warsaw surrendered to the Germans on September 27, with final pockets of resistance surrendering on October 6. About 100,000 Polish military personnel were evacuated to Romania and the Baltic countries; many of these soldiers later fought against the Germans in other theaters of the war. Poland's Enigma code breakers were also evacuated to France.

After the direct borders between Germany and the Soviet Union were created, the Soviet-German Non-Aggression Pact was signed, giving the Soviets freer hand on the Baltics. The Soviet Union then began to force the Baltic countries to allow it to station Soviet troops in their countries under pacts of "mutual assistance." Finland and Estonia rejected territorial demands and were invaded by the Soviet Union in November 1939. The resulting Winter War ended in March 1940 with Finnish and Estonian concessions.

In December 1939, the United Kingdom won a naval victory over Germany in the south Atlantic during the Battle of the River Plate.

Western Europe (1940-41)
Following the pressures from the United Kingdom and France, Scandinavia issued an iron embargo to Germany that critical for the latter's wartime production of steel on February 1940. As result, Germany invaded Scandinavia on April 1940. Copenhagen was easily captured after a few hours and the royal family was evacuated to Bergen. Despite Allied support, during which the important harbor of Narvik temporarily was recaptured by the British, Scandinavia was conquered within two months. The United Kingdom then occupied the Scandinavian possessions of Madagascar, Iceland, Greenland and the Faroes to preempt a possible German invasion of the islands. A discontent over the Norwegian campaign within the British Parliament led to the replacement of the British Prime Minister, Neville Chamberlain, with Edward F. L. Wood, 1st Earl of Halifax on May 10, 1940.

France was invaded by Germany from north and Italy and Spain, that declaring war on both France and the United Kingdom, from south on 10th and 11th of May 1940 respectively. For reasons of military strategy, Germany also attacked the neutral nations of Belgium, the Netherlands, and Luxembourg. The Netherlands and Belgium were overrun using blitzkrieg tactics in a few days and weeks, respectively. Allied defense that focused more on northern Maginot Line resulted the Spanish-Italian forces to cross the Pyrenees Line on the south and the Alpine Line on the southwest easily. In the north, the main body the Allied forces which had moved into Belgium were also circumvented by a flanking movement through the thickly wooded Ardennes region. As a result, the bulk of the Allied armies found themselves trapped in an encirclement and were beaten.

Allied troops were forced to evacuate the continent at Dunkirk, abandoning their heavy equipment by early June. Paris fell on June 10 and eight days later France surrendered. France was soon divided into German, Spanish, and Italian occupation zones, and an unoccupied rump state under the Vichy Regime, which, though officially neutral, was generally aligned with Germany. France kept its fleet but the British feared the Germans would seize it, so on 3 July, the British attacked it.

In June 1940, the Soviet Union forcibly annexed Latvia and then annexed the Romanian region of Bessarabia after the Germans earlier launched an offensive against Lithuania that heightened the tension between both countries. Despite already signed a non-aggression pact, however, after successful Germany's invasions of Scandinavia and France, both Germany and the Soviet Union began preparations for war against each other.

On July 19, 1940, Germany offered to end the war with the British. However, Lord Halifax blatantly rejected the offer. Germany responded by starting an air superiority campaign over the United Kingdom, known as the Battle of Britain, to prepare for an invasion. The campaign failed, and the invasion plans were cancelled by September. Frustrated, and in part in response to repeated British air raids against Berlin, Germany began a strategic bombing offensive against British cities known as the Blitz. However, the air attacks largely failed to either disrupt the British war effort or convince them to sue for peace.