A Bulgarian tsar rode into battle waving the treaty his enemy broke
When Theodore Komnenos Doukas invaded Bulgaria in 1230 despite a peace deal, Tsar Ivan Asen II led his reserve troops, including 1,000 Cuman horse archers, into battle at Klokotnitsa with a copy of that treaty held high on a pole. The surprise charge won the day and made Bulgaria the leading power in south-eastern Europe.
Ivan Asen was born in the 1190s, son of Ivan Asen I, one of the leaders of the 1185 uprising against Byzantium that created the Second Bulgarian Empire. His father was murdered by a nobleman in 1196, and his uncle Kaloyan was killed in 1207 while besieging Thessaloniki. The teenage heir lost out to a cousin, Boril, who married Kaloyan's widow, and he fled north to the lands of the Rus.
Boril never secured his rule. After years in exile, Ivan Asen gathered a band of soldiers, possibly paid for by Boril's enemies, and returned, besieging the capital Tarnovo until its people surrendered in 1218. A chronicler claimed the siege lasted seven years, though most historians think he confused months with years. When the Hungarian king Andrew II came home from crusade that year, Ivan Asen would not let him pass until he promised his daughter Maria in marriage, with the Belgrade region as dowry.
He played the neighbouring powers against each other. He escorted a new Latin emperor across Bulgaria in 1221, offered his daughter to the boy emperor Baldwin II hoping to become regent in Constantinople, and after Klokotnitsa swept through Thrace, Thessaly and much of the western Balkans. In 1235 he allied with John III Vatatzes of Nicaea, and the head of the Bulgarian Church was raised to patriarch. When he realised Nicaea stood to gain most from toppling the Latins, he dropped the alliance in 1237.
Controlling the Via Egnatia trade road filled his treasury. He opened a mint in Ohrid striking gold coins, enlarged the palace on Tsarevets Hill and built the Church of the Holy Forty Martyrs in Tarnovo to celebrate his victory. An inscription there calls him tsar of the Bulgarians, Greeks and other lands, and he sealed documents with gold, imitating Byzantine emperors. He died in May or June 1241.
Source: Ivan Asen II
