1 Samuel 11:1 - The Popular Commentary by Paul E. Kretzmann

Then Nahash, the Ammonite, the king of the children of Ammon living in the territory east of Jordan, came up, undertook a campaign of war, very likely with the object of avenging his people for the defeat administered to them by Jephthah, Judges 11:32, and encamped against Jabesh-gilead, in the valley east of Jordan, about halfway between the Sea of Galilee and the Dead Sea; and all the men of Jabesh, who were apparently suffering with the same lack of courage which caused their fathers to stay away from the campaign against Benjamin, Judges 21:8-9, said unto Nahash, Make a covenant with us, and we will serve thee. They wanted to have some reasonable conditions under which they could become tributaries to the Ammonites. This answer is characteristic of Israel's weakness, of the utter lack of a conscious and permanent union between the various tribes. It was a very loose confederacy indeed where such conditions were possible.