In 1993, when President Bill Clinton signed the policy known as “Don’t Ask, Don’t Tell” into law, it represented a compromise between those who wanted to end the longstanding ban on gays serving in the U.S. military and those who felt having openly gay troops would hurt morale and cause problems within military ranks. Under the new policy, gay, lesbian and bisexual Americans could serve their country, as long as they kept their sexual identity under wraps.

Though supporters of “Don’t Ask, Don’t Tell” welcomed it as a more liberal policy that would allow gay Americans to serve their country, gay rights activists complained that it forced these service members into secrecy, while doing little to combat the prejudice against them. Meanwhile, the military continued to discharge thousands of gays and lesbians from service.

Amid mounting opposition to “Don’t Ask, Don’t Tell,” President Barack Obama announced its repeal in mid-2011, ending 17 years of secrecy and silence for lesbian, gay and bisexual members of the U.S. military.

Though the U.S. military did not officially exclude LGBTQ service members from its ranks before the mid-20th century, “homosexual acts” were grounds for discharge as far back as the Revolutionary War. In the aftermath of World War I, the military made the act of sodomy a crime subject to punishment by a court-martial.

As the nation prepared for World War II, and many psychiatrists classified homosexuality as a mental or behavioral disorder, potential servicemen began undergoing psychiatric screening as a part of the induction process. In 1942, military regulations began listing homosexuality as an excludable characteristic for the first time.

Despite this policy, hundreds of thousands of gays and lesbians served in the military throughout the next several decades, keeping silent about their sexual identity for fear of being discharged, losing their veterans’ benefits or worse.

The ban withstood challenges from the growing gay rights movement in the 1970s, including a high-profile lawsuit filed by Technical Sergeant Leonard Matlovich, who was discharged from the U.S. Air Force after admitting he was gay in 1975. In 1981, the Department of Defense reaffirmed the ban, and during the 1980s the military branches discharged close to 17,000 men and women under the homosexual category.

During his 1992 presidential campaign, Bill Clinton announced his intention to end the ban on homosexuals in the military if elected. Gay rights supporters rejoiced, but the new president’s efforts met with stiff bipartisan opposition in Congress. As reported in the Atlantic, documents released by the Clinton Library in 2014 about the debate included handwritten notes suggesting that Colin Powell, then chairman of the Joint Chiefs of Staff, argued strongly for keeping the ban in place. But over the course of the debate, the notes revealed, Powell suggested that a “possible solution” could be that “we stop asking.”

On July 19, 1993, Clinton announced the “Don’t Ask, Don’t Tell” (DADT) policy, which permitted gay Americans to serve in the military as long as they remained closeted. The policy, enshrined in a federal statute passed by Congress the same year, went into effect in February 1994.

Under DADT, military personnel were not allowed to discriminate against or harass closeted service members they believed to be gay. On the other hand, homosexual or bisexual service members could not disclose their sexual orientation or refer to any same-sex relationships. If they violated this policy, or otherwise were found to have engaged in “homosexual conduct,” they would be subject to discharge.

Though Clinton admitted the policy was “not a perfect solution,” he presented it as a “major step forward” from the existing ban. But many gay rights activists criticized the policy as falling way short, claiming DADT did little to promote acceptance of gays and lesbians within the military. The statute itself concluded that homosexuality, if openly acknowledged, “would create an unacceptable risk to the high standards of morale, good order and discipline, and unit cohesion that are the essence of military capability.”

Opposition to DADT mounted over the years, especially after the 9/11 terrorist attacks, as the United States began fighting wars in both Afghanistan and Iraq. In practice, the policy did little to change the behavior of commanding officers toward service members they suspected of being gay, and by 2009, the military had discharged more than 13,000 gays, lesbians and bisexuals since DADT was introduced, according to the Servicemembers Legal Defense Network.

In 2010, just after Senate Republicans blocked a repeal effort, Clinton himself voiced regret over the policy, and said he had only settled on it after it became clear both the Senate and the House would favor an absolute ban on gays in the military.

Barack Obama campaigned for president in 2008 with a promise to immediately overturn DADT, but the discharges continued during his first year in the White House. By 2010, several U.S. states (including Massachusetts, Connecticut, Vermont and New Hampshire) had legalized same-sex marriage.

Later that year, the Pentagon announced the results of a report aimed at determining how a repeal would affect the military, and some 70 percent of U.S. service members surveyed said a repeal would have mixed, positive or no impact. Finally, that December, the House and Senate passed a repeal of DADT, which Obama signed into law on December 22.

After the repeal became official on September 20, 2011, it seemed to have a domino effect on other longstanding barriers within the armed forces. In 2013, the Pentagon announced it would lift the ban on women serving in ground-combat units. In 2015, the Pentagon added sexual orientation to the Military Equal Opportunity policy for the first time, meaning gay servicemen and servicewomen would be protected from discrimination.

In June 2016 the military ended its ban on transgender service members, a group that according to some estimates may have numbered some 15,500 at that time. Though in March 2018, President Donald Trump signed a memorandum that banned some transgender people from U.S. military service.