What does Judges 11:26 mean?
The Ammonites are encamped against Israel and ready to go to war against Gilead, east of the Jordan River (Judges 10:17–18; 11:4). The king of Ammon claims his cause is just, suggesting the Israelites took the land from his people centuries earlier (Judges 11:14).Jephthah has offered three counterarguments to show that this is wrong. First, the Ammonites did not even possess the land of Gilead when Israel took possession of it (Judges 11:14–22). Second, it was the Lord that gave the land to Israel, meaning that it belonged to them by God's divine will (Judges 11:23–24.) Third, kings more prestigious than the current king of Ammon knew better than to try to take Gilead from Israel. That included Balak, the famous king of Moab during that time (Judges 11:15).
The fourth argument is simply one of time; it has been multiple generations since Israel has occupied this territory. Israel has had villages all over Gilead during that entire time. If the Ammonites truly had a claim on the land, why did they wait three centuries to try to take it back? Wouldn't they have attacked hundreds of years earlier if they believed this to be true? An implied aspect of Jephthah's claim here is an accusation: that the king of Ammon is simply lying. Noting the long delay before any action was taken suggests Ammon's king is fabricating this claim to the land, trying to fool others into thinking his war is a just one.