Joshua 4:11-13

11and when all the people had finished crossing, then the ark of the Lord and the priests crossed in front of the people. 121The sons of Reuben, the sons of Gad, and the half-tribe of Manasseh crossed over in battle formation before the sons of Israel, just as Moses had spoken to them; 13about forty thousand equipped for war, crossed for battle before the Lord to the desert plains of Jericho.