The Ammonites: Assisted Eglon Against Israel
Source: TTT
Judges 3:12, 13
Once again the Israelites did evil in the sight of the LORD. So He gave Eglon king of Moab power over Israel, because they had done evil in the sight of the LORD. / After enlisting the Ammonites and Amalekites to join forces with him, Eglon attacked and defeated Israel, taking possession of the City of Palms.