 He led 40,000 men, hidden until the last minute by fog, over the pass, and dispersed the Phoceans who were guarding the pass.However, the Phoceans informed the Greek army at Thermopylae in time to safely retreat before encirclement.The Athenian fleet evacuated the army, and Brennus marched for Delphi, not waiting for Acichorius and the rest of the army to catch up.