David wanted to complete the conquest of Canaan begun by Joshua. He defeated the Jebusites at Jerusalem and the Philistines in the vicinity of Gath. The Ammonites, Arameans, and Moabites became his subjects. He put garrisons in Edom and levied a tax upon them. They later joined forces to swoop down on Philistia to the west. King Sargon of Assyria captured the Philistine city of Ashdod.