1 Samuel 13:5 (ESV)

5 And the Philistines mustered to fight with Israel, thirty thousand chariots and six thousand horsemen and troops like the sand on the seashore in multitude. They came up and encamped in Michmash, to the east of Beth-aven.

Michmash was about 10 kilometres north of Jerusalem, in the territory of Benjamin and close to the town of Gibeah (where Saul lived).1