On a bright, warm day 50 years ago this week, three young men went out to have a drink that they hoped would make history.

The men, members of the early gay rights group the Mattachine Society, aimed to challenge bars that refused service to gay people, a common practice at the time, though one unsupported by any specific law. Such refusals fell under a vague regulation that banned taverns from serving patrons deemed “disorderly.”

“At the time, being homosexual was, in itself, seen as disorderly,” said Dick Leitsch, 81, reminiscing the other day in his apartment on the Upper West Side of Manhattan.

Mr. Leitsch, then the head of Mattachine’s New York chapter, and his cohorts called their action a “Sip-In,” a tipsy tip of the hat to the civil rights lunch-counter sit-ins then being held at places that segregated black patrons. The Sip-In was a pivotal moment for the gay rights movement, predating the Stonewall uprising by more than three years. That it is largely forgotten says a lot about how the gay political conversation has shifted over the past five decades.