The Book of Deuteronomy Chapter 20:1-4
1 When thou shalt go forth to war against thine enemies, and shalt see horses and chariots, and people more than thou, be not afraid of them: for the Lord thy God is with thee, which brought thee out of the land of Egypt. 2 And when ye are come near unto the battle, then the Priest shall come forth to speak unto the people, 3 And shall say unto them, Hear, O Israel, ye are come this day unto battle against your enemies: let not your hearts faint, neither fear, nor be amazed, nor a dread of them. 4 For the Lord your God goeth with you, to fight for you against your enemies, and to save you.
Consider also this day in your study Deuteronomy 7:21, 28:7; 2 Samuel 22:31-33; Psalm 18:30-32