“long war.” The wars of Joshua lasted seven years (Josh. 14:7-10). Besides that, the full conquest was little by little (Exod. 23:29-30; Deut. 7:22). This in part explains how it was that when Joshua conquered a city but then he and his army left the area, Canaanites moved back into the cities. Evidence from the testimony of Caleb shows that the conquest lasted seven years. Caleb was 40 years old when he spied out the Land, spent 38 years in the wilderness (until age 78), and 85 when he was given his inheritance at Hebron. Seven years of being on the march and in war after war is a very long time.
“a long time.” The Hebrew is literally “many days.”