An organization representing the gay community announced Friday that it would march in the South Boston St. Patrick's Day Parade on Sunday, a final sign that the storied event is ending its longstanding refusal to include gay groups.
The decision by parade organizers to include Boston Pride, best known for holding its own parade in June celebrating lesbian, gay, bisexual, and transgender dignity, comes nearly 20 years after the US Supreme Court affirmed parade organizers' right to exclude gay groups.
It follows the organizers' recent decision to allow a gay veterans group to march, prompting several local politicians to say they would drop their refusal to participate in the parade and join in as well.
"We are wicked proud of . . . finally breaking that wall," said Sylvain Bruni, president of Boston Pride. "It's a huge change, especially 20 years later, to have that understanding and make sure people feel welcome in the parade. And we look forward to having this participation for years to come."
Parade coordinator Tim Duross said the Allied War Veterans Council, organizer of the 114-year-old parade, recently reviewed and voted on the application from Boston Pride as it would any other.
"I think the council has gone far beyond what they've done in the past," Duross said. "But let's hope for the best, and maybe this will be the end of all this."
Boston Mayor Martin J. Walsh, who last year tried unsuccessfully to negotiate the inclusion of a gay rights group, announced earlier this week he would become the first Boston mayor in two decades to march in the parade because organizers had embraced another group, OUTVETS, which honors LGBT veterans.
"I'm thrilled that the St. Patrick's Day parade is inclusive this year, and the addition of Boston Pride to the list of participants reflects the values of the South Boston neighborhood," Walsh said in a statement Friday. "With this year's parade, Boston is putting years of controversy behind us."
Governor Charlie Baker, Suffolk County Sheriff Steven W. Tompkins, US Senator Edward J. Markey, and US Representative Seth Moulton also have announced plans to march.
The group's participation was not universally welcomed. In an apparent response to the announcement, the Massachusetts State Council of the Knights of Columbus announced that it will not march, saying the event had "become politicized and divisive."
In an undated message on its website, the Catholic fraternal organization said, "We deeply regret that some have decided to use this occasion to further the narrow objectives of certain special interests, which has subjected this occasion to undeserved division and controversy."
The parade has become a battleground for the gay rights movement in recent decades, after organizers sought to bar marchers from the Irish-American Gay, Lesbian, and Bisexual Group of Boston.
The US Supreme Court ruled in 1995 that the march was a privately organized event protected by the First Amendment right to freedom of speech: organizers could include — or reject — any group.
Organizers have argued that gay people have always marched. The prohibition, they contended, was not against the gay community but against political statements about sexual orientation or other issues.
After Walsh's negotiation efforts collapsed last year, gay marchers participated in at least two contingents, though they marched with South Boston community groups rather than as part of a gay rights organization.
This year, after organizers accepted the application from OUTVETS, Boston Pride decided for the first time to apply to march, Bruni said.
"We thought it was really important for us to step forward and say we want the whole LGBT community to be represented in the St. Patrick's Day parade," he said.
Bruni said he received a call Friday from an Irish-American gay man in his late 40s who said, on the verge of tears, "For the first time, I will be able to march in the parade and celebrate my heritage openly, without any fear."
Duross said some paradegoers might be offended by Boston Pride's inclusion. But the group agreed to abide by rules that say all marchers must refrain from overt political messages or "any expression of sexual orientation," Duross said.
"We don't think that's a topic that should be in our parade," Duross said. "We're asking that they respect our parade and our heritage and our community. And I think they will. I hope they will."
Duross said past controversies had cast an unfairly negative light on parade organizers.
"Everyone knows a gay person or has a gay person in their family," he said. "We're offended when people say that we're antigay. We're not antigay. We never have been."
Bryan Bishop, cofounder of OUTVETS and chief of staff in the city of Boston's Veterans Services Department, stressed that his group is apolitical and focused on supporting and recognizing the contributions of LGBT veterans.
But, he said, he was pleased to hear the group called "a catalyst" in bringing progress.
"We're very proud to have been the leaders in the forefront of change and inclusiveness in this wonderful parade," Bishop said. "Our hope is that we have a wonderful day on Sunday, we have a great parade . . . and everyone is respectful of what the Allied War Veterans Council and the people of South Boston have put together."
Moulton, who served four tours as a Marine in Iraq, announced Wednesday that he plans to march with OUTVETS.
"Gay rights is the civil rights fight of our generation," Moulton said in a statement.
Markey also plans to march, he said Friday.
"Today marks a remarkable moment as we come together to celebrate the contributions and service of our veterans and the diversity of the great city of Boston," Markey said in a statement. "The Council's decision to allow Boston Pride and OutVets to march in this year's parade is an historic moment for the city, the Commonwealth, and the country."
Martin Finucane and Andrew Ryan of the Globe staff contributed to this report. Jeremy C. Fox can be reached at email@example.com. Follow him on Twitter @JeremyCFox.