Probably 50 years ago
To refresh your memory, it’s a story about a man named Billy Pilgrim that is an involuntary Time Traveler.
He pops in and out of different times of his life but not in sequence.
He was a soldier and POW in WWII. He would be in the POW camp on day and wake up in his life 10 years ahead or 30 or or 40 or backwards. He had no control over it.
The title, Slaughterhouse Five, was the name of the building that the POWs were kept in at one point, being moved from place to place due to the war............