The children of Israel again did that which was evil in the sight of Yahweh; and Yahweh delivered them into the hand of the Philistines forty years.
It is amazing that the Philistines gave their name to the Holy Land, Palestine.  In the times of the Judges, which we are studying, the Philistines were strong enough to be a continual threat to Israel.  Shamgar had opposed them earlier, but the defeat of the powerful Ephraimites by Jephthah had effectively removed any significant opposition to the Philistines.  And they dominated Israel for a long period of time reaching down through the judgeship of Samuel, the kingship of Saul, and until the times of David who completely subdued them.