The watchmen of Saul in Gibeah of Benjamin looked; and, behold, the multitude melted away, and they went [here] and there.
"The Hebrews who had been with the Philistines"  (1 Samuel 14:21).  When the Israelites forsook Saul and left him with only 600 men, this verse indicates that large numbers of them had joined the Philistines; but when it was evident that Israel was winning a great victory, they promptly changed sides again and turned against the Philistines.  Also, all of those Israelites who had been hiding in the holes, caves, cisterns, etc., poured out of their hiding places and joined in the pursuit of the enemy.