And they warred against the Midianites, as the LORD commanded Moses; and they slew all the males.
Now therefore kill every male among the little ones, and kill every woman that hath known man by lying with him. But all the women children, that have not known a man by lying with him, keep alive for yourselves. Numbers 31:7, 16-17
And the children of Israel did evil in the sight of the LORD: and the LORD delivered them into the hand of Midian seven years. And the hand of Midian prevailed against Israel.
For they came up with their cattle and their tents, and they came as grasshoppers for multitude; for both they and their camels were without number. Judges 6:1-2, 5