The conflict that produced the Second Battle of Lamia grew out of Rome's First Macedonian War — a conflict in which Rome, deeply entangled in the struggle against Carthage, chose to keep Philip V busy by subsidizing his enemies in Greece rather than fighting him directly. The Roman proconsul Marcus Valerius Laevinus had sailed from Corcyra, forged an alliance with the Aetolian League, and begun picking at Philip's Aegean assets. In the spring of 210 BC, Laevinus and the Aetolians captured Anticyra in Phocis: Rome enslaved the inhabitants and Aetolia kept the town, a division that troubled some allies even as the coalition grew. Pergamon, Elis, Messenia, and eventually Sparta all agreed to join against Macedon. The Roman and Pergamene fleets between them commanded the sea, and Philip found himself threatened on multiple fronts. The strategy was working well enough that when Laevinus returned to Rome to take up his consulship, he could report that the legion deployed in Greece could safely be withdrawn.

Despite the impressive roster arrayed against him, Philip moved with the energy that defined his reign. Through 210 BC the Eleans, Messenians, and Spartans remained largely passive — coalition members on paper who did not press the war in practice — and Philip exploited the gap. He besieged and took Echinus using extensive siege works, beating back a relief attempt by the Aetolian commander Dorimachus and the Roman fleet now under Publius Sulpicius Galba. Moving west, Philip probably also seized Phalara, the port town on the Maliac Gulf that served as Lamia's outlet to the sea. In the spring of 209 BC, Philip's Achaean allies in the Peloponnese were under pressure from Sparta and the Aetolians, and word came that Attalus of Pergamon had been elected a supreme commander of the Aetolian League — and might be sailing west from Asia Minor with his fleet. It was precisely this accumulation of pressures that drove Philip south. Near Lamia, he had already defeated Pyrrhias once that year, inflicting close to a thousand Aetolian casualties in the First Battle of Lamia.

Pyrrhias came to the fight again supported by Pergamene forces and Roman advisors — the same mixture that had been insufficient before. The result was the same: he was defeated, his forces suffering heavy casualties. The source record for the battle is thin — Polybius and Livy note it without dwelling on the tactical detail — but the outcome was clear enough. Pyrrhias could not break Philip's momentum on land regardless of how many allies signed treaties in Rome's interest. The battle was a demonstration of the gap between diplomatic coalition-building and military reality: a coalition that included Rome, Pergamon, and most of the Peloponnese could still be outfought on a Greek plain by a Macedonian king moving fast and decisively. The plain near Lamia, repeatedly contested across the decades, absorbed another clash and kept its indifference to the politics that drove men to fight there.

The First Macedonian War never became the decisive confrontation Rome had perhaps hoped for. Philip managed his multiple fronts with enough skill that neither side achieved the knockout blow that would have changed the map dramatically. The war wound toward a peace in 205 BC — the Peace of Phoenice — that left most of the belligerents where they started. For the Greek poleis that had allied with Rome, it was a sobering education in what Roman partnership actually meant: their towns could be enslaved and their ports seized for Roman strategic convenience, the alliance papers notwithstanding. Philip, for his part, drew the lesson that the Greek states could not reliably hold together long enough to threaten him, and turned his attention elsewhere. A second, more decisive confrontation with Rome would come later — culminating at Cynoscephalae in 197 BC — but near Lamia in 209 BC, the immediate question was settled: Pyrrhias would not be winning a battle there.