WASHINGTON — The Senate unanimously voted to pass a bill to reform military sexual assault policy Monday, bringing an end to an almost year-long battle between two Democratic female senators on how best to overhaul the Pentagon’s existing practices.

After New York Sen. Kirsten Gillibrand’s radical proposal to remove the chain of command from sexual assault prosecution narrowly failed to gain the 60 votes it needed to advance Thursday, the path was cleared for Missouri Sen. Claire McCaskill’s measure. The bill passed 97 – 0.

The Missouri Democrat’s bill would eliminate the “good soldier” defense for service members accused of assault, under which troops argued strong military records supported their innocence. It also would give victims a say in whether military sexual assaults committed on bases would be tried in a military or civilian court.

“This debate has been about one thing — getting the policy right to best protect and empower victims, and boost prosecutions of predators. I believe we’re on the cusp of achieving that goal,” McCaskill said after the Senate voted to advance her bill Thursday. “The Senate has voted to strengthen even further what is now one of the most victim-friendly justice systems in the world.”

McCaskill’s reforms come after she helped shape the annual defense bill to curb military sexual assault last year. The measures enacted in the December bill revoke a commander’s ability to overturn jury convictions and required a civilian review when a commander does not prosecute a case.

“This is a continuation of the work we did with the defense bill, but it is not the end of it,” said New Hampshire Sen. Kelly Ayottte, a co-sponsor of McCaskill’s bill.

Gilllibrand wanted to go further in eliminating the power of commanders to influence sexual assault cases in their units. Her measure would have moved sexual assault cases to an independent prosecutor within the military.

McCaskill, a former courtroom prosecutor of sex crimes, staunchly opposed Gillibrand’s overhaul of the chain of command, saying it “falls short.” That bill received only 54 of the 60 votes it needed to clear parliamentary hurdles and move forward, with 17 of the 20 female senators backing it.

Gillibrand said the Senate “failed” victims of military sexual assault in a statement Thursday. She acknowledged advancements had been made through the defense bill and McCaskill’s Victims Protection Act.

“But we have not taken a step far enough,” Gillibrand said. “We know the deck is stacked against victims of sexual assault in the military, and today, we saw the same in the halls of Congress.”