Deuteronomy 20:1

When thou goest out to battle against thine enemies The land of Canaan being to be gained by conquest, in a war of God's special appointment; and the Israelites, after their settlement in it, being likely to be exposed to invasions from, or quarrels with the neighbouring nations, Moses judged it necessary to leave them some standing rules for their conduct in both these kinds of war. The first and great rule was, to commit their cause to God, depending with entire confidence upon that divine power which had so often and so wonderfully delivered them, without the least fear or discouragement at the superior force or terrible appearance of their enemies. And seest horses and chariots The armies of the Israelites consisted wholly of foot, and their law seems to have obliged them to continue so, in order that their reliance might be entirely on God, Deuteronomy 17:16. But the Egyptians, Canaanites, and other nations, had the advantage of horses and chariots, in which they placed their confidence. Thus the psalmist: “Some trust in chariots and some in horses, but we will remember the name of the Lord our God.” These chariots were sometimes armed with scythes, to rush in among the foot, and cut them down like grass, which made them very formidable. These are the chariots of iron, mentioned Judges 4:3.