In the following decades, the Malians were under the hegemony of Sparta until they revolted against Sparta in the Corinthian War. In this war, they lost their land south of the Spercheios, Herakleia Trachis was given to the Oitaians, and Lamia became the new capital of the Malians. A Malian, Ephialtes of Trachis, betrayed the Spartans and their allies in the Battle of Thermopylae, helping the Persians surround the Greek army. Together with the Oitaians and the Ainians, the Malians became members of the Corinthian League and, in 235 BCE, the Aetolian League. In 189 BCE they were joined to Achaea Phthiotis and since that time the Malians were regarded as Thessalians.