Mr. McConnell grew up in a close extended family that accepted him for who he was. He was pursuing a master’s degree in library science when he first met Mr. Baker at a barn party in Norman, Okla., in 1966. He was immediately attracted, Mr. McConnell recalled, but also wary: Why did this man have a severe flattop, and why was he so serious?

Mr. Baker, whose haircut was a remnant of an aborted military career, was immediately won over, and he started asking Mr. McConnell on dates to the theater and movies.

Mr. Baker had been orphaned at age 4 and spent nearly 12 years at a Catholic boarding school in Illinois. In college, he joined the Air Force, which put him through an engineering degree. But he was forced out before receiving his officer’s commission when an airman complained about an unwanted advance.

Mr. Baker enrolled in law school at the University of Minnesota in 1969, keeping his promise to Mr. McConnell that he would figure out a way to marry.

There, he became the first president of FREE, for Fight Repression of Erotic Expression, which was among the country’s earliest college organizations for gay rights. The group fought to hold gay and lesbian dances on campus and forced corporate recruiters to pledge not to discriminate in hiring.

Mr. McConnell joined him and was promised a position at the University of Minnesota Libraries.

Doing research in his first year of law school, Mr. Baker discovered that the state’s marriage law at the time did not mention gender. So on May 18, 1970, in white shirts and matching ties, the men entered the Hennepin County Courthouse, applied for a marriage license and paid the $10 fee. They had alerted journalists and made national news.