Byzantine–Bulgarian wars
Bulgarian civil wars

Soon after the Byzantine empire was restored under Michael VIII Palaiologos, he became involved in a civil war in Bulgaria. Michael gave his support for Ivan Asen and sent several Byzantine armies to assert him on the throne. Ivailo, the current Bulgarian ruler, defeated several of these attempts, but he was blockaded for three months in Drăstăr (Silistra) by the Mongol allies of the Byzantine emperor. In the meantime, a Byzantine force besieged the Bulgarian capital and, after hearing a rumor of Ivailo's death in battle, the local nobility surrendered and accepted Ivan Asen III as emperor in 1279.

Shortly after this, still in 1279, Ivailo suddenly appeared before Tărnovo with an army, but he failed to take the well-fortified city. He nevertheless defeated a larger Byzantine relief force near Varna and another in the Balkan passes. Desperate for relief, Ivan Asen III fled Tărnovo in 1280, and his brother-in-law, George Terter I, seized the throne, uniting the factious aristocracy and gradually taking away the support for Ivailo.
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