The Battle of Ctemwnae was a brief military encounter between Athens and Thessaly over a selection of petty indifferences that eventually brought the two nations to war. Alexander, who was the cruelest despot of his time, had repeatedly violated his peoples right and eventually that of a foreign nation, imprisoning Timotheus in a act of anger against an Athenian emissary. The result was a Athenian-led invasion of Thessaly, commanded by Timotheus's son, Helmetrus.
Alexander, who believed he could defeat Athens on his own ground, was beaten badly by more experienced Athenian troops, many of whom had fought in Timotheus's wars in Southern Greece. Despite a slight numerical Thessalian numerical advantage, Alexander was crushed under Helmetrus's army, and was forced to make terms, freeing several political prisoners (including Timotheus) and a large reparation sum to Athens.