From the advocate.com:
For the gay patrons of the Black Cat tavern in the Silver Lake neighborhood of Los Angeles, it was a disheartening start to 1967. As balloons dropped from the ceiling to mark the New Year, undercover cops ripped Christmas decorations from the walls, brandished guns, then beat and cuffed 14 people. Two men arrested for kissing were later forced to register as sex offenders; one bartender suffered a ruptured spleen. Violent police raids on queer bars weren’t uncommon in the ’60s, but this time the gays didn’t let it slide.
Interestingly, this event helped to create The Advocate magazine.
And it is not the only bar of that name to have made GLBT history. Read about the Black Cat Bar in San Francisco