WASHINGTON — The women of the Senate who led the fight to change how the military deals with sexual assault in its ranks are hailing passage of a comprehensive defense bill that now heads to President Barack Obama for his signature.

The Senate voted 84-15 Thursday night for the $632.8 billion bill that covers combat pay, new ships, aircraft and military bases. Drawing the greatest attention were provisions cracking down on perpetrators of sexual assault and rape.

The military’s handling of high-profile cases united Democrats and Republicans, House and Senate in a concerted effort to change the Uniform Code of Military Justice, with Senate women leading the fight. Estimates from the Pentagon that 26,000 members of the military may have been sexually assaulted last year, though thousands were afraid to come forward for fear of inaction or retribution, emboldened lawmakers to act.

“Today represents a huge win for victims of sexual assault, and for justice in America’s armed forces, but this is no finish line,” said Sen. Claire McCaskill, D-Mo., one of seven women on the Armed Services Committee who pushed for the changes. “In the months and years ahead, vigilance will be required to ensure that these historic reforms are implemented forcefully and effectively.”

The legislation would strip military commanders of their ability to overturn jury convictions, require a civilian review if a commander declines to prosecute a case and require that any individual convicted of sexual assault face a dishonorable discharge or dismissal. The bill also would provide victims with legal counsel, eliminate the statute of limitations for courts-martial in rape and sexual assault cases, and criminalize retaliation against victims who report a sexual assault.

“Today we have taken a major, unprecedented step toward finally eliminating the plague of sexual assault in our nation’s military,” said Sen. Patty Murray, D-Wash.

Another member of the Armed Services panel, Sen. Kelly Ayotte, R-N.H., said the special counsel “will help encourage victims to come forward to seek justice, and it will help ensure that perpetrators are held accountable for their crimes.”

The bill also would change the military’s Article 32 proceedings to limit intrusive questioning of victims, making it more similar to a grand jury, a change backed by Sen. Barbara Boxer, D-Calif., and Sen. Lindsey Graham, R-S.C.

Boxer said the changes will ensure “that victims of sexual assault are not put on trial simply for making the courageous decision to pursue justice.”

The congressional effort was marked by one of the most contentious hearings, when senators dressed down senior military leaders and insisted that sexual assault in the military had cost the services the trust and respect of the American people as well as the nation’s men and women in uniform.

Summoned to Capitol Hill in June, Army Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, and the beribboned four-star chiefs of the service branches conceded in an extraordinary hearing that they had faltered in dealing with sexual assault. One said assaults were “like a cancer” in the military.

Members of the Senate Armed Services Committee, especially Sens. Kirsten Gillibrand, D-N.Y., and McCaskill, grilled the chiefs about whether the military’s mostly male leadership understands differences between relatively minor sexual offenses and serious crimes that deserve swift and decisive justice.

“Not every single commander necessarily wants women in the force. Not every single commander believes what a sexual assault is. Not every single commander can distinguish between a slap on the ass and a rape because they merge all of these crimes together,” Gillibrand said.

The legislation does not include a contentious proposal from Gillibrand to give victims of rape and sexual assault in the military an independent route outside the chain of command for prosecuting attackers, taking the authority away from commanders.

That proposal drew strong opposition from the Pentagon and several lawmakers. Gillibrand’s plan is likely to get a separate vote, perhaps as early as next month.

The bill would give Obama additional flexibility in deciding the fate of terror suspects at the detention center at Guantanamo Bay, Cuba, but it stops well short of the administration’s goal of closing the installation.

Congress has passed a defense policy bill every year since the Kennedy administration, but the 52nd year has been one of the more tortuous as the legislation got caught up in the dispute between Republicans and Democrats over Senate rules and limits on debate.

The White House had expressed support for the legislation, which would provide $552.1 billion for the regular military budget and $80.7 billion for the war in Afghanistan and other overseas operations, a reflection of deficit-driven efforts to trim spending and the drawdown in a conflict lasting more than a decade.

The legislation also would cover combat pay and other benefits, authorize funds for the destruction of chemical weapons in Syria and provide money to study the feasibility of establishing a missile defense site on the East Coast.