Ivan Asen II, also called John Asen II (Bulgarian: Иван Асен II, [1190s – May/June 1241), ruled as Emperor (Tsar) of Bulgaria from 1218 to 1241. He ascended to power as a young child after his father, Ivan Asen I, a key figure in founding the Second Bulgarian Empire, was killed in 1196. Despite attempts by his supporters to claim the throne following the murder of his uncle, Kaloyan, in 1207, Ivan Asen was initially thwarted by his cousin, Boril. Forced to flee Bulgaria, he sought refuge in the Rus' principalities. Boril struggled to maintain control, creating an opportunity for Ivan Asen to rally an army and reclaim his position. By 1218, he seized Tarnovo and subjected Boril to blinding. Initially aligning with the Papacy, he formed alliances with nearby Catholic powers like Hungary and the Latin Empire of Constantinople. He attempted to secure regency for the 11-year-old Latin Emperor, Baldwin II, after 1228, but faced opposition from the Latin nobility. His significant victory over Theodore Komnenos Doukas in the Battle of Klokotnitsa in 1230 led to the collapse of Theodore's empire and Ivan Asen's expansion into territories spanning Macedonia, Thessaly, and Thrace. Controlling trade along the Via Egnatia, Ivan Asen initiated an ambitious construction program in Tarnovo and minted gold coins in his newly established mint in Ohrid. Negotiations about the Bulgarian Church's return to Orthodoxy commenced after the barons of the Latin Empire appointed John of Brienne as regent for Baldwin II in 1229. Collaborating with Emperor John III Vatatzes of Nicaea, Ivan Asen forged an alliance against the Latin Empire during a meeting in 1235. At this gathering, the Bulgarian Church was granted the status of autocephaly (independence) with the rank of patriarch bestowed upon its leader. However, Ivan Asen eventually broke ties with Nicaea in 1237, realizing that Vatatzes might primarily benefit from the downfall of the Latin Empire. Following the Mongol invasion of the Pontic steppes, several Cuman groups sought refuge in Bulgaria.

Ivan Asen II - Wikipedia