Armies of Different Nations often Confederated

…they came together to wage war against Joshua and Israel.

So the five kings of the Amorites—the kings of Jerusalem, Hebron, Jarmuth, Lachish, and Eglon—joined forces and advanced with all their armies. They camped before Gibeon and made war against it.

After enlisting the Ammonites and Amalekites to join forces with him, Eglon attacked and defeated Israel, taking possession of the City of Palms.

Now Ben-hadad king of Aram assembled his entire army. Accompanied by thirty-two kings with their horses and chariots, he marched up, besieged Samaria, and waged war against it.