ISRAEL’S WARS—By God’s command, the Israelites were to take possession of the Promised Land by conquest, thoroughly cleansing all wicked idolators from the land of God’s people.
The Israelite conquest of this land held by Canaanite tribes was led by Joshua and lasted a long time (Joshua 11:18)—about seven years.
“God turned the Canaanites’s hearts to fight [Joshua 11:20] in order that Israel might be His judging instrument to destroy them. They were willfully guilty of rejecting the true God with consequent great wickedness and were as unfit to remain in the land as vomit spewed out of the mouth (Leviticus 18:24-25).” —Dr. John MacArthur, The MacArthur Study Bible
Except in the case of Jericho and Ai, the war did not become aggressive till after the death of God’s man Joshua. Till then the attack was always first made by the Canaanites. Now the measure of the iniquity of the Canaanites was full, and Israel was employed by God to sweep them away from off the face of the Earth.
In entering on this new stage of the war, the tribe of Judah, according to divine direction, took the lead.
In the days of Saul and David the people of Israel engaged in many wars with the nations around, and after the division of the kingdom into two they often warred with each other. They had to defend themselves also against the inroads of the Egyptians, the Assyrians, and the Babylonians. The whole history of Israel from first to last presents but few periods of peace.