No details are given as to how Saul fared against the Philistines.1 Most likely he went to fight off a raiding party, similar to what David did when he rescued Keilah (1 Samuel 23:1–29). The fact that he had three companies of men available to join him in his pursuit of David suggests that his campaign was met with success.2
1 When Saul returned from following the Philistines, he was told, “Behold, David is in the wilderness of Engedi.”