The country and the army declined after Ivan Asen II's death. His successors could not cope neither with the external nor with the internal problems. Mongol, Byzantine and Hungarian invasions were combined with separatism among the nobility and several civil wars. In 1277, a peasant named Ivailo rebelled against Emperor Constantine Tikh. In the ensuing battle the Emperor was defeated and slain, and Ivailo proclaimed himself Emperor of Bulgaria in Tarnovo. Although he managed to defeat both the Mongols and the Byzantines, a plot among the nobility forced him to seek refuge among the Mongol Golden Horde, where he was killed in 1280. The army now numbered less than 10,000 men — it is recorded that Ivailo defeated two Byzantine armies of 5,000 and 10,000 men, and that his troops were outnumbered in both cases.