Albert Barnes Commentary 1 Samuel 13:2

"Saul chose him three thousand men of Israel, whereof two thousand were with Saul in Michmash and in the mount of Beth-el, and a thousand were with Jonathan in Gibeah of Benjamin: and the rest of the people he sent every man to his tent." — 1 Samuel 13:2 (ASV)

The situation preceding the events described in this chapter seems to have been a time of relative peace between Israel and the Philistines, since Saul had only 3,000 men under arms.

At the same time, Philistine garrisons continued to occupy certain strongholds in the land of Israel. One of these was at Geba (Jeba), in the immediate vicinity of Gibeah (1 Samuel 10:5; 1 Samuel 13:3) and directly opposite Michmash (Mukhmas), which was on the northern edge of the great Wady Suweinit.