Albert Barnes Commentary 1 Samuel 14:31

"And they smote of the Philistines that day from Michmash to Aijalon. And the people were very faint;" — 1 Samuel 14:31 (ASV)

Aijalon. The modern Yalo. It lies on the side of a hill to the south of a fine valley that opens from between the two Bethhorons, extending down to the western plain of the Philistines. This is the exact route the Philistines would have taken to return to their own country after being expelled from the high country around Michmash and Bethel. Aijalon is approximately 15 to 20 miles from Michmash.