The Thessalians originally sided with Antipater, but were quickly persuaded to join the Athenians as allies. Together, they defeated Antipater at Thermopylae. The defeated Macedonians fled to the fortified city of Lamia, where they were besieged by the Athenians as Antipater waited for reinforcements to arrive from Asia. The Athenians and their allies, despite their early successes, were bogged down in their siege of Lamia. The well-walled town proved impregnable to the Athenians, and their commander Leosthenes was mortally wounded during a sallying forth from the city by the Macedonians who sought to harass their ditch-digging besiegers. His death prompted the Athenians to retreat.