The consul Lucius Mummius, whom the senate had resolved to send to Greece, had not yet arrived; accordingly Metellus undertook to protect Heraclea with the Macedonian legions.

When the advance of the Romans was announced to the Achaeo-Theban army, there was no more talk of fighting; they deliberated only how they might best succeed in reaching once more the secure Peloponnesus; in all haste the army made off, and did not even attempt to hold the position at Thermopylae.
But Metellus quickened the pursuit, and overtook and defeated the Greek army near Scarpheia in Locris.

The loss in prisoners and dead was considerable; Critolaus was never heard of after the battle.
The remains of the defeated army wandered about Greece in single troops, and everywhere sought admission in vain; the division of Patrae was destroyed in Phocis, the Arcadian select corps at Chaeronea; all northern Greece was evacuated, and only a small portion of the Achaean army and of the citizens of Thebes, who fled in a body, reached the Peloponnesus.

Metellus sought by the utmost moderation to induce the Greeks to abandon their senseless resistance, and gave orders, for example, that all the Thebans with a single exception, should be allowed their liberty; his well-meant endeavours were thwarted not by the energy of the people, but by the desperation of the leaders apprehensive for their own safety.

Diaeus, who after the fall of Critolaus had resumed the chief command, summoned all men capable of bearing arms to the isthmus, and ordered 12,000 slaves, natives of Greece, to be enrolled in the army; the rich were applied to for advances, and the ranks of the friends of peace, so far as they did not purchase their lives by bribing the ruling agents in this reign of terror, were thinned by bloody prosecutions.