March 19–Battle of Adramyttion: The Byzantine army, under Constantine Laskaris (brother of Theodore I), appears before the walls of Adramyttium – surprising the Latin garrison. Meanwhile, Henry of Flanders, not wanting to remain trapped within the city, opens the gates and charges out with his heavy cavalry. He and his knights defeat the Byzantine forces, who are scattered and forced to retreat.[2]
March– Byzantine officials in Adrianople revolt and expel Latin administrators, requesting Bulgarian support from Kaloyan, ruler (tsar) of the Bulgarian Empire, against Baldwin I who assembles an army (some 40,000 men) and marches to aid the Byzantines. Meanwhile, Baldwin sets out from Constantinople in force, he arrives at Adrianople and promptly begins to siege the city by the end of March.
April 14–Battle of Adrianople: Latin forces under Baldwin I are defeated and eliminated in a successful ambush by Bulgarians, Vlachs and Cumans. Baldwin is captured and taken as prisoner to Veliko Tarnovo – where he is locked up at the top of a tower in the Tsarevets fortress. Later, Baldwin is possibly executed by orders of Kaloyan (this according to the Byzantine historian George Akropolites).[3]
May 29–Andrew II, brother of the late King Emeric, is crowned ruler of Hungary and Croatia at Székesfehérvár, after his 5-year-old nephew, Ladislaus III, suddenly dies in Vienna. Andrew introduces a new policy for royal grants, which he calls "new institutions". He distributes large portions of his domain–such as royal castles and all estates attached to them–to supporters and Hungarian nobles.[6]
Summer – King Philip II (Augustus) conquers most of the Angevin lands, including much of Aquitaine. Fearing a French invasion of England itself, King John (Lackland) requires every English male over 12 years to enter a mobilization "for the general defense of the realm and the preservation of peace". John prepares an expedition force of his own, but the barons refuse to cross the Channel.[8]