(Devarim 24:5) "If a man take a new wife": This tells me only of a virgin. Whence do I derive (the same for) a widow and a divorcée? From (Ibid.) "and he shall rejoice his wife" — in any event. If so, why is it written "new"? One who is "new" to him — to exclude a returned divorcée.
"he shall not go out in the army": I might think that he does not go out into the army, but he supplies to it weapons, food, and water; it is, therefore, written "and it shall not impose upon him for any thing." I might think (that it may not impose upon him) even if he built a house and inaugurated it, planted a vineyard and redeemed it, betrothed a woman and took her (viz. Ibid. 20:5-6); it is, therefore, written "upon him." It does not impose upon him, but it does impose upon the aforementioned.
"Free shall he be for his house" — his house;
"shall he be" — his vineyard;
"and he shall rejoice his wife" — a (new) wife;
"whom he has taken" — to include his yevamah.