The “city of palms” is Jericho, which was the first city in Canaan to be conquered by Israel under Joshua and dedicated to the Lord. Now it is lost again to the enemy—a clear testimony to Israel of what they had turned into. Furthermore, it was the Israelites who were supposed to take possession of the land, rather than the enemy taking possession of it!
13 He gathered to himself the Ammonites and the Amalekites, and went and defeated Israel. And they took possession of the city of palms.