Fearing the rapid success of Ivaylo's revolt in Bulgaria, Michael VIII summoned Ivan Asen, a descendant of Bulgaria's ruling dynasty living at the Byzantine Empire (he was the son of Mitso Asen, who reigned in 1256–57), granted him the title of "despotes", and married him to Irene in 1277 or 1278. Michael VIII then sent several Byzantine armies in an attempt to install Ivan Asen III on the throne. This caused an alliance between Ivaylo and the dowager Bulgarian empress Maria Kantakouzene: she married Ivaylo, who was recognized as Bulgarian emperor in 1278, without deposing or disinheriting the young Michael Asen II, her son by the late Constantine Tikh, whom Ivaylo killed at the beginning of the revolt. Although Ivaylo defeated several of Michael VIII's attempts to depose him, he was blockaded for three months in Drăstăr (Silistra) by the Mongol allies of Michael VIII. In the interval a Byzantine force besieged the Bulgarian capital, Tarnovo, and, hearing a rumor of Ivaylo's death in battle, the local nobility surrendered and accepted Ivan Asen III as emperor in 1279 and Irene became the new empress consort of Bulgaria.