Updated

Marine 1st Lt. Brandy Soublet is about as far from the war front as possible at her desk in the California desert, but she's on the front lines of an experiment that could one day put women as close to combat as their male peers.

The Penfield, N.Y. woman is one of 45 female Marines assigned this summer to 19 all-male combat battalions. The Defense Department in the past year has opened thousands of combat positions to women to slowly integrate them and gauge the impact such a social change would have on the military's ability to fight wars.

No branch is likely to feel that change more than the Marine Corps.

The small, tight-knit force is the most male of the armed services and prides itself on having the toughest and most aggressive warriors. The Corps historically has higher casualty rates because it is considered to be the "tip of the spear," or the first to respond to conflicts. It also was among the last military branches to open its doors to women, forming the first female Corps in 1943, according to the Women's Memorial in Washington D.C.

But changing times are challenging the traditions of the force, long likened to a brotherhood.

Modern warfare has put women in combat like never before over the past decade, even though a 1994 policy bars them from being assigned to ground combat units below the brigade level, which were considered too dangerous since they are often smaller and closer to combat for longer periods.

Already under pressure to provide the same opportunities for women, the Defense Department was hit Tuesday with a second lawsuit by female service members -- including two Marines -- charging that the gender barriers unfairly block them from promotions open to men in combat.

The lawsuits are intended to accelerate the military's slow march toward lifting the ban that plaintiffs allege has barred women from 238,000 positions.

Defense officials say they recently opened 14,500 jobs to women, and they need to move cautiously to ensure the change will not disrupt wartime operations. Soublet and the other 44 women are part of the quiet, slow transformation. Women make up about 7 percent of the Marine Corps compared to about 14 percent overall among the military's 1.4 million active military personnel

She said some Marines initially eyed her pioneering presence in the all-male battalion with skepticism.

"The way that I would describe it to friends and family was it was kind of like I showed up to work in a costume," the 25-year-old logistics officer said in a phone interview from Twenty-Nine Palms, a remote desert base east of San Diego. "They stared a little bit but after a while it wasn't like that anymore."

That experience may play out on bases and boats worldwide as the Pentagon levels the battlefield.

The Corps earlier this year opened its grueling infantry officer training school to female Marines and surveyed 53,000 of its troops with an anonymous online questionnaire about the impact of erasing gender barriers. Survey results are expected to be released soon after review by the defense secretary.

Only two female Marines volunteered for the 13-week infantry training course at Quantico, Va., and both failed to complete it this fall. No women have volunteered so far for the next course offered in January, officials said.

Soublet said she was nervous she would feel unwelcome in the combat engineer battalion.

Six months into her historic assignment, she said she has been treated equally.

"I have heard, you know, whisperings, like `Hey, before you got here we decided to maybe take down some pictures and clean up our language a little bit,' but other than that, they haven't really expressed anything to me," said Soublet, who will remain two years in her battalion and is expected to deploy with them to Afghanistan this spring.

The Marine Corps Commandant Gen. James F. Amos said he met with the top leaders of the 19 battalions and told them to establish the proper command climate. The early steps of assigning females to artillery, tank, combat engineer and other all-male battalions have been successful, but there may be some anxiety if women join infantry, Amos said.

Camp Pendleton combat Marine Carlos Laguna, who left the Corps in 2011, agreed.

"The screams of women, they have a big psychological effect on men. A woman just has a different pitch," said Laguna, who suffers from post-traumatic stress disorder after two tours in Iraq. "If we're in a firefight and a woman is shot or lost her arm, male Marines like me would want to stop and help. It's our nature to help women."

The survey addressed those concerns, asking males if they would be distracted or "feel obligated to protect female Marines." It also asked whether women would be limited because of pregnancy or personal issues.

Female Marines were asked if they would feel pressured to suppress their femininity.

Former Marine Capt. Kristen Kavanaugh, who runs The Military Acceptance Project, a San Diego-based organization promoting equality in the services, found those questions offensive.

"I don't think women who signed up to give their life for their country are worried about the appearance of their femininity," she said.

Former Camp Pendleton Marine Capt. Anu Bhagwati was only the second woman to complete a martial arts instructor training school, earning a black belt in close combat techniques. But she said years of discrimination caused her to quit in 2004.

"I learned early on that the Marine Corps will expect you to fail if you are a woman," said the head of the Service Women's Action Network, which helped the women file the lawsuit. "I faced so much discrimination and sexual harassment that it made me wonder why I was serving."

Soublet said in her three years in the Corps she has found her fellow Marines to be respectful and professional.

"This isn't a big deal," she said. "We're Marines, we're here to do a job and it doesn't matter what our gender is."