From Charles Vincent de Vet (1911-1997), American science fiction writer, Second Game (1981):
You cannot win the war. You will seem to win but it will be an illusion. You will win the battles, kill billions, rape Worlds, take slaves, and destroy ships and weapons. But after that you will be forced to hold the subjection. Your numbers will not be expendable. You will be spread thin, exposed to other cultures that will influence you, change you. You will lose skirmishes, and in the end you will be forced back. Then will come a loss of old ethics, corruption and opportunism will replace your honor and you will know unspeakable shame and dishonor… your culture will soon be weltering back into a barbarism and disorganization which in its corruption and despair will be nothing like the proud tribal primitive life of its first barbarism. You will be aware of the difference and unable to return.