The young Bulgarian Tzar, Michael II Asen, exploited Vatatzes' death to reconquer the lands he had seized from Bulgaria after 1241. Michael invaded Macedonia and Thrace in December 1254 or January 1255. Most Nicaean garrisons at the fortresses were small, and the local Bulgarians supported the invaders. The Bulgarians quickly seized most Thracian fortresses. Two Macedonian towns, Veles and Skopje, also surrendered to them. A hastily summoned council of war accepted George Mouzalon's proposal of an immediate counter-attack. Theodore decided to lead the campaign himself, and entrusted Mouzalon with the administration of Asia Minor in February 1255. His surprise attack forced the invaders to withdraw from Thrace, and he ordered two aristocrats, Alexios Strategopoulos and Demetrios Tornikes, to chase the Bulgarians. The two generals led their troops across the passes of the Rhodope Mountains in constant fear of an ambush. When they unexpectedly heard the sounds of the horns of shepherds and swineherds, they broke into a run in panic, abandoning their baggage. The fiasco outraged Theodore, and he ordered them to hurry to his camp at Adrianople, but both commanders disobeyed.