Invasion of Baltic (Premysloides Dynasty)

Background
Imperial rule over Mazuria fall in 1332. While Roman Empire maintain rule over Latvia province, they lost Mazuria and their influence over Lithuania and Russian states was weakened. From 1332 to 1367, Mazuria was important treasury for anti-Imperial struggle and as war continued, anti-Emperor Stephen decided to expand Saint Atlantis territory to eastward, especially more on Baltic shores.

Preparations for invasion started 1365 when Stephen for first time discussed this intention with his lords and dukes. In this years, Imperial Civil War and Pan-European War was nearly at end - Free Cities Commonwealth was defeated, Bohemia became staunchly loyal to Saint Atlantis, most imperial loyalists of Hohenstauf Dynasty were killed and Hohenstauf forces remained only in Austria and northern Italy, where they still fought for last Holy Roman Empire Emperor Conrad I.

Stephen want to expand his lands before end of war, as he did not have enough sources and forces to wage war against Roman Empire and their allies, but he can conquer remaining Baltic provinces of Roman Empire.

Stephen was able to quickly summon large army. Grand Commonwealth army was already summoned, as Grand Commonwealth conquered in 1365 Hamburg and remaining Free Cities and was in stance to continue war. Grand Commonwealth army was led by constable Gunter of Sweisshaus and commander de Guesclin.

Another military force already in battle stance, was Teutonic Crusader Army, massive military force builded with help of Mazurian Duchy since 1332. About 7,000 infantry and 1,000 knights and aristocrats loyal to Teutonic Order.

Mazuria provided hiring of mercenaries, even few remaining Cuman tribes in Hungary, which joined polish forces, as Stephen offered recognition of Casimir bastard son Pelko as rightful and legitimate heir for polish participation in this invasion. Casimir accepted this generous offer and sent his army under his own command.

Remaining forces were gathered from various lands of Saint Atlantis, even from Bohemia.

What Stephen and his allies did not know was that Imperial Military Intelligence was much more developed and effective since 1332 and was able to infiltrate Stephen ranks for many years. Emperor Arcadius who was not interest in military affairs assigned Stratégos Iulianos, commander of Balkan Military District, to assist Supralegatus Theophanes, commander of Baltic District. He sent emissars to Russians and Mongolians, as Mongolians owned favor to Roman Empire and Russians wanted to strenghten their ties with Roman Empire.

Also Baltic pagans and remaining troops and militiamen of Free Cities joined defending army, Free Cities troops wanted revenge for Hamburg defeat.

Invasion
First and very important success of defenders was assassination of commander Bertrand du Guesclin. Imperial Intelligence had dossier about du Guesclin as talented military commander and expert on so-called "Fabian Strategy", which was strategy that Iulianos wanted to use against invaders. If du Guesclin would live, he would be able to recognize this strategy and applicate countermeasures.

Aside of that, Iulianos wanted to use tactic of scorched earth and guerilla warfare against invaders. He was very firm to avoid direct confrontation as far as he can. Scouts and local armed bandits and peasants infested forests in Baltic territories and waited for invading army, while most of imperial army slowly retreated to Vilnius area. About quarter of defenders remained on borders and in western parts to delaying invasion.

Iulianos goal was to delay confrontation after winter, because invasion has started during September 1367. Invasion army attacked imperial defenders on 27 September 1367 and conquered Barštynas, they found city empty. Except garrison defending town, everyone else was away and also all supplies and food. All wells were contaminated by excrements. Identical situation happend in Rastenburg, Geldap and Alytus.

Soon, guerilla groups started raid invasion army encampments and fortifications, killing knights, lords, barons, poisoning supplies, or using trumpets, drums and whistles to disrupt sleeping of invaders. This delayments and disruptions provide enough time for defenders to unite their armies with Russian and Mongolian reinforcements and to complete final drafts of their battleplan.

Battle of Vilnius
Final battleplan determined confrontation at Vilnius, or Kaunasus. Defending army was dislocated near tradepost Gelvonay and waited on signal. About half of their forces were split in to defend of Kaunas and Vilnius, as one, or both of these cities will be probably invasion targets. However, invasion advance was stopped at early December because of severe winter. Both sides suffered under these conditions, but defenders had supplies and support from local population, while invaders were on hostile territory and without any help, cut off from supply lines. Defenders lost about 800 troops during winter, while invaders lost 2,500 troops, but it was only small fraction of armies.

Delayment had another effect. Stratégos Iulianos ordered supralegatus Kankydze to gather charcoal, sulfur, saltpeter, oil and sodium to mix enhanced gunpowder. Most of these ingredients were supplied by Russian merchants and artisans and were used to craft explosives. Tons of explosives were planted all over Vilnius and Kaunas, in all houses, most districts, except few where will be fortified garrisons, to sewers and streets.

Attack on Vilnius began 26 February 1368 when weather conditions improved and when invading army morale was weakened by lack of food. Winrich could not wait anymore and marched on Vilnius. At night 26 February, invading army reached Vilnius and attacked city. Defenders started feign retreat in to town citadel, where was about 4,000 defending troops. At midnight, most of invading army was in Vilnius and about 70% of town was conquered and invaders stopped right above and near explosives. Kankydze, who commander Vilnius garrison, while Theophanes led Kaunas garrison, now ordered his troops to shot fire arrows and grenades to planted explosives.

Only very few shots and grenade attacks were necessery to ignite chain reaction of explosives. Three-quarters of city was destroyed by inferno that engulfed invading army. House by house, district by district, everything fall in to flames and at early morning, city were charred ruins, except citadel and center of town.

Counter-attack
Counter-attack was started by explosion in Vilnius. This explosion was also signal for dislocated defending army. Army under command of Iulianos went on march and cavalry was able to block off escape route for invaders, who ran from Vilnius inferno. Infantry arrived shortly after and all ways for invaders were blocked. 12,000 surviving invaders surrendered to imperials. 40,000 died in inferno, or shortly after during clash with Mongols, but this campaign did not end.

Contrary. Stratégos Iulianos wanted to use total destruction of enemy in regain lost holdings and expand imperial territory. By 17 March, Mazuria was conquered with very small resistance. Danzig was captured 22 March. Slupsk and remaining Pomeranian was captured 27 March. Imperial counter-attack was stopped at Sczeczin in West Pomeranian. Bloody battle and resistance in Sczeczin led to death about 8,000 imperial troops and stopping counter-invasion, as Iulianos knew he would not be able to maintain more expanded territories.

Aftermath
Instead, Emperor Arcadius and anti-Emperor Stephen signed peace treaty. Sczeczin was split as border city in two halfs, eastern under Roman Empire rule, western under Saint Atlantis rule, Stephen has to pay tribute 6,000 pounds of gold and declare truce for 50 years, recognize territorial losses and new Roman rule over conquered territories.

Victorious imperial counter-invasion persuaded Russian princes to join Roman Empire and Roman Empire expanded to Republics of Novgorod and Pskov and to Principalities Yaroslavl, Smolensk, Polotsk and Ryazan. This connection with northern fur trade and new wealthy lands had deep positive impact on imperial economy and led to building "Kirkuk-Constantinople-Narva Trade Magistrale", one of longest and most prosperous trade route in Europe.