There is nothing wrong with the sentence:
Another great war could destroy victor and vanquished alike. Equally you could write:
Another great war could destroy the victor and the vanquished alike.
I prefer the first.
Do you know the saying: Who goes there, friend or foe? We never say: Who goes there, a friend or a foe?
Recently, in another context, Soup said language goes from the complex to the simplex. That is to say anything that can be left out without compromising the meaning content will or can be.