Rupert Cornwell: Before Stonewall, there was Frank Kameny

Out of America: The American gay rights pioneer, who died last week, had been fighting against homophobic laws for more than half a century

A genuine and uniquely American hero died here in Washington last week. You've probably never heard of Frank Kameny. But for his courage and his perseverance, some have compared his importance to the gay rights movement with Rosa Parks, even Martin Luther King, in the struggle for civil rights.

Today, it's hard to imagine the social climate back in 1957, when Kameny was thrown out of his job as an astronomer for the Army Map Service after five months because he was gay. Unlike in Britain, where until 1967 homosexual acts in private were a crime, they were never technically illegal at a federal level here.

But owing to an executive order by President Eisenhower in 1953, "sexual perversion" was enough to get you sacked from government service. Until 1973 homosexuality was medically classified as a sickness, a "psychiatric disorder", and not until 2003 did a landmark Supreme Court judgment strike down anti-sodomy laws still in force in several southern states. Even in liberal DC, anti-sodomy legislation was not repealed until the mid-1990s.

It's tempting to compare Kameny with Alan Turing, the brilliant wartime code-breaker at Bletchley Park and father of modern computer science, who was convicted for homosexual behaviour, stripped of his security clearances and subjected to chemical castration so as to avoid jail. Broken and humiliated, Turing committed suicide in 1954.

Kameny was different – as may be gathered from this description of him in Out for Good, a 1999 history of the gay rights movement by Dudley Clendinen and Adam Nagourney. He had "the confidence of an intellectual autocrat, the manner of a snapping turtle and a voice like a foghorn", the authors write. With a PhD from Harvard, Kameny was wont "to express himself in thunderous bursts of precise and formal language, cultivating the self-righteous arrogance of a visionary who knew his cause was just even when others did not".

He was certainly not a man to be cowed by power – even when plain-clothes agents of DC's Perversion Squad were infiltrating meetings of the Mattachine Society of Washington, an early gay advocacy group that Kameny helped to found. He got around that problem by having activists operate under aliases.

At first the fightback got nowhere. Courts dismissed his appeal against his firing, and in 1961 the Supreme Court refused to take up his case, the first ever to claim a violation of civil rights because of sexual orientation. His treatment, Kameny's petition said, was "an affront to human dignity". But this only firmed his resolve.

And in typically American fashion, Kameny realised that publicity was his friend. In 1965 he led a march outside the White House to protest against the treatment of gay federal employees. The Johnson administration responded by issuing a letter justifying their dismissals on the grounds of the "revulsion of other employees". But already Kameny's slogan "Gay Is Good" had became a mantra.

Suffice it to say that Kameny was far ahead of his time. The Stonewall riots after a police raid on a gay bar in New York – the generally acknowledged start of the gay rights movement – did not take place until June 1969. And only in 1977 did Harvey Milk – subject of a terrific movie starring Sean Penn – become the first openly gay man elected to public office, in the San Francisco city government.

Gradually Kameny's efforts bore fruit. In December 1973, the American Psychiatric Association passed a resolution saying that, "by itself", homosexuality was not a psychiatric disorder. There followed repeal of anti-sodomy laws by individual states and finally the admission of openly gay people into the armed forces.

In the old days, "perverts" had to lie to become soldiers. "They asked, I didn't tell," Kameny said in an interview in May 2010, speaking of his enlistment into the military in 1943. In 1993, President Bill Clinton tried to change the law, but had to settle for the "Don't Ask, Don't Tell" compromise. Last month, DADT was finally rescinded, capping a banner year for gay rights here, in which New York became the seventh state (including DC) to recognise gay marriage.

In 2009 Kameny received a formal apology from the federal government for his original sacking from the Army Map Service. "It took 50 years, but I won my case," he said. By coincidence or otherwise, 2009 was also the year that Alan Turing received a posthumous apology from Gordon Brown for his "appalling treatment".

But arguably the greatest tribute came six months ago, when documents relating to Kameny's case were included in an exhibit at the Library of Congress called Creating the United States. "I guess you can say I have become one of the creators of the US, which I would never have imagined in 1961," he declared.

Frank Kameny's legacy is immense, not least because he helped so many talented Americans to hold high positions in government. Fittingly, he died last Tuesday. It was 11 October, or National Coming Out Day.