What does 1 Samuel 13:11 mean?

Samuel asked, 'What have you done?' Saul answered, 'I saw my men leaving, you hadn't come when you said you would, and the Philistines were gathering at Michmash.' 1 Samuel 13:11 - Modern Text Bible

(Samuel confronts Saul, who tries to justify his actions by blaming the situation and Samuel's delay.)