TOS s2e15 “The Trouble with Tribbles”
It’s any wonder there wasn’t a second Klingon/Federation major conflict prior to the Dominion’s presence after Scotty transported the mass of tribbles from the Enterprise onto the outgoing Bird of Prey right before warping away. But hey, gotta end it on a light-hearted moment.
Obviously the canon explanation is now that it was all caused by the Augment Virus. However, what they SHOULD have done for the explanation was say that the Klingon Empire is an EMPIRE, composed of many planets across vast regions of space, and that the Empire therefore included many conquered species, all of whom shared the demonym “Klingon” in the interests of imperial unity. TOS Klingons could then have been explained as one of the conquered species who embraced their new Klingon culture wholeheartedly, and the redesigned Kelvin Timeline Klingons could have shared that same explanation.
Acceptance of diversity could then be said to be why Klingons and the Federation get along so well, since they both share the same vision of galactic harmony, but the Klingons simply believe this can only be achieved through conquest.
The old Roman Empire, just like the new Klingon Empire. I like it.
I love it.
Back in the day, Ho Chi Minh was legally a Frenchman, not a citizen of Vietnam.