In life, Major Alan G Rogers was an American patriot, committed to the US Army in which he had served for 18 of his 40 years. His death this year, from a roadside bomb, which took the number of American losses in Iraq to more than 4,000, robbed the service of an outstanding military intelligence officer and deprived his friends of someone they all described as a great listener and a profoundly religious man.

Major Rogers was also gay. He wasn't asked and, at least to most colleagues, he didn't tell, but the story of his struggle to balance two competing aspects of his life has moved to the heart of the debate about gay military service.

Alan Rogers, raised by adoptive parents in New York and Florida, joined the US Army to serve in the 1991 Gulf War, and later had tours of South Korea and Iraq ahead of the 2003 invasion. He used military sponsorship programmes to pursue academic studies, ultimately becoming a biometrics expert on assignment at the Pentagon before his final tour of duty in Iraq. He was also a Baptist preacher and is remembered as a wise counsellor to friends and men under his command.

Major Rogers' story has been adopted by gay-rights campaigners. Someone on a computer inside the Pentagon was briefly able to change a Wikipedia profile of Major Rogers to omit his sexuality, sparking a battle over whether it was relevant to notices of his long service and his ultimate sacrifice.

"Alan was a true soldier and loved serving his country," his friend Tony Smith remembered. "And he was also a gay man. Alan was not someone who hid his sexual orientation. He didn't wear it on his sleeve, but he didn't hide it under a cloak either."

Now, campaigners hope that the example of this dedicated military man, posthumously awarded a Purple Heart for his sacrifice, is giving new impetus to their attempt to rip up the Clinton-era policy known as don't ask, don't tell and finally to allow gays and lesbians to serve openly in the US military. It was a campaign of which Rogers had been a part in life, and which has taken a few faltering steps towards fruition in the short months since his death in January. Although a slim majority of active military personnel still oppose a change, surveys have shown a significant warming towards the idea of repeal, at a time when the US is stretched thin in two wars. Last week, Congress held a hearing on the policy for the first time since it was put on the statute books 15 years ago.

"I think the momentum is there now for change," says Denny Meyer, editor of The Gay Military Times, an online newsletter that advocates a repeal of don't ask, don't tell. His and other lobby groups have adopted the story of Major Rogers to encourage supporters to contact politicians and push for change. "Rightnow we have generals and admirals who have served 20 or 30 years who have come out. Gay people have been serving in America's armed forces since the Revolution – but Major Rogers is the first known homosexual to have been killed."

At home in Washington, he was treasurer of the capital's chapter of American Veterans for Equal Rights, which campaigns to allow gays to serve openly, and he wrote an academic thesis dissecting don't ask, don't tell. But when friends mentioned his sexuality in local newspaper reports after his death, it came as a surprise to former colleagues in the Pentagon.

Cathy Long, his cousin, has joined some military personnel to express displeasure that Major Rogers's story has been adopted by gay-rights campaigners. Activists, though, say that it is precisely by highlighting the sacrifices of gay servicemen and women that they will be able eventually to win the battle to be accorded the same rights to be open about their sexuality as straight colleagues.

Last week's hearing before the House of Representatives Armed Services Personnel Sub-committee was attended by Eric Alva, an Iraq veteran with a Purple Heart who was the first US soldier to be injured during the invasion. While he testified in favour of repealing don't ask, don't tell, the hearing was more notable for the suggestions of Elaine Donnelly, head of the Centre for Military Readiness, who said any change would probably increase the incidence of HIV among service members – and the subsequent ructions among lawmakers, who rounded on her.

Although many US allies allow gays and lesbians to serve openly, and the UK has allowed it since 2000, top Pentagon officials remain opposed. Senator John McCain says he is opposed on the grounds that it will damage morale, but his rival for the presidency, Barack Obama, says he supports the repeal of don't ask, don't tell.