Numbers 31:49 - Ellicott's Commentary On The Whole Bible

There lacketh not one man of us. — It is obvious from the smallness of the number of the Israelitish warriors, as well as from the reference to those chiefs only of the Midianites who were the vassals of Sihon, and from the strength of the Midianitish nation in the time of Gideon (Judges 6-8), that the attack was made only upon that particular portion of the nation which had been concerned in the seduction of the Israelites to the worship of Baal Peor. The Midianites were probably attacked in an unprepared and defenceless state. After due allowance, however, has been made for all these circumstances, the fact that not a single Israelitish warrior perished can be satisfactorily explained only on the supposition that God vouchsafed to grant to His people miraculous aid and protection.