I adore the Man-Kzin Wars series. The series is a shared universe so multiple authors write several short stories set in the universe in each book.
The plots revolve around the theme of:
Mankind has socially conditioned itself to be absolute pacifists. Human space was in the middle of the "Long Peace". ARM, the United Nations security force, has completely suppressed all "dangerous" technologies, histories, mental illnesses, and media, leading to not only an end of war and almost all violent crimes, but a change in society so vast that most people have a difficulty even conceptualizing such things. They have started space exploration and colonization and encounter the alien species the Kzinti a warrior race of giant bipedal tiger/lions that conquer other alien species to use them as slaves/prey animals for their hunting reserves. The Humans as a result have to relearn war, and the Kzinti learn that humanity isn't a race of pacifists because they don't know how to fight, but because they were so good at fighting they had to become pacifists to prevent their own self-destruction.
There are a lot of books in the series and because its written by multiple authors you can pick up any of them and just start reading.
Its a fun read <: