(Ibid. 20:13) "Then the L-rd your G-d will deliver it into your hands": If you do all that has been stated, in the end, the L-rd your G-d will deliver it into your hands.
"then you shall smite all of its males by the sword": I might think, even the children; it is, therefore, written (Ibid. 14) "but the women and the little ones … you shall take for yourself": — But perhaps the little ones of the females are meant! — Can you say this? Now if (in the war with) Midian, where the adult women were put to death, the little ones were spared, then here, where the adult women were spared, how much more so would the little ones be spared (and no verse would be needed to tell us that). It must be, then, that "little ones" here refers to the little ones of the males.