During the Klingon-Federation War of 2372-73
the two sides fought a brief but bloody and bitter war. And it prompts me to make both some observations and ask some questions.
First an observation, as quickly as they were enemies, they were friends again. Now, it seems to me that was a little too clean and simple that the two sides got along as friction-free as they did, after the war, necessity for an alliance against the Dominion notwithstanding. Sure, one can possibly explain the Klingons were able to put aside any grudges after the war was over if for no other reason than out of respect for Starfleet holding its own, and the fact that in Redemption, the Klingons would fight each other by day in the Klingon Civil War, and drink together by night. War and battle was just business and nothing personal. But for Starfleet members, it was personal: a former ally turned on them and started attacking them. Did anyone else have a problem with that?
But most of all, imagine if you will, and taking all the other powers out of the equation (especially the Dominion, the war kept on going. Who would have won in that time frame? Would it have been a replay of Yesterday's Enterprise, with the Klingons projected to eventually defeat the Federation, or would it have been different?