12 The Reubenites, Gadites, and the half-tribe of Manasseh had crossed over in battle formation in front of the People of Israel, obedient to Moses' instructions. 13 All told, about 40,000 armed soldiers crossed over before God to the plains of Jericho, ready for battle.
Matthew Henry's Commentary on Joshua 4:12-13
Commentary on Joshua 4:10-19
(Read Joshua 4:10-19)
The priests with the ark did not stir till ordered to move. Let none be weary of waiting, while they have the tokens of God's presence with them, even the ark of the covenant, though it be in the depths of adversity. Notice is taken of the honour put upon Joshua. Those are feared in the best manner, and to the best purpose, who make it appear that God is with them, and that they set him before them.