Solzhenitsyn said that there's nothing worse for a country than to win a big war. This is filtered a little through my own perception, but the best I remember it was that winning a war teaches the lesson that all the maniacs were right and gives them all kinds of confidence to let them do more of the same, which never ends well at home or abroad. He said that usually if a country loses a big war, it comes out of it with some wisdom, and regards any maniacs at home or abroad with deep visceral suspicion from then on, which is as it should be.