Over the past nine months, the Marine Corps tested a gender-integrated task force in both Twentynine Palms, Calif. and Camp Lejeune, N.C. in an attempt to gauge what the Corps might look like with women in combat roles.

According to a recent report in the Marine Corps Times, only a small number of women were left by the experiment’s conclusion — two of the roughly two dozen who started — mostly in part because of the physical and mental stress that comes with combat roles. Both the men and women in the task force also reported a breakdown in unit cohesion with some voicing  a perceived unequal treatment from their peers.

The experiment comes as all branches of the military face a Jan. 1 deadline to open all combat positions to women — from basic infantry battalions to elite special operations units such as U.S. Navy SEALs. While branches like the Air Force and Navy have relatively small communities where women are currently barred from serving — namely special operations detachments — the U.S. Army and Marine Corps have a host of units and jobs closed to women. These jobs, known as combat arms, include infantry, artillery and armored divisions.

The gender-integrated Ground Combat Element Task Force served as a snapshot of sorts of what the Marine Corps might look like if women were a staple in combat positions. Each closed position was represented: infantry, artillery and mechanized units, such as tank platoons and light armored reconnaissance detachments, all operated in tandem with one another. The women were spread among them in ratios that would be expected in an integrated Marine Corps, with roughly 90 percent of the branch made up of men.

The nine-month exercise was broken down into two parts. Initially there was a four-month training period, or “work-up,” at Camp Lejeune, followed by a five month “deployment” to the Mojave Desert in Twentynine Palms. Certain elements of the task force also participated in training at Camp Pendleton, and mountain warfare in Bridgeport, Calif.  This two semester cycle was common over the past 15 years. During the height of the Iraq War, it was common that Marine units would train for six to eight months and then deploy for a similar amount of time.

During both phases of the training, the Marines were hooked up to heart monitors and equipment that monitored their shooting abilities. According to the report, the data will be sent to Marine Commandant Gen. Joseph Dunford in order to better tailor his approach to integrating women into Marine combat positions and help establish a baseline for gender-neutral standards that the Marines can possibly apply in the future.

Yet for all the monitoring technology in the field, most of the feedback, both negative and positive, has thus far been anecdotal.

“[The Marine Corps] hope[s] to provide transparency to our research and findings soonest,” Marine spokesman Maj. Christian Devine wrote in an e-mail.

The Marine Corps Times report cites a number of instances where women had a difficult time completing physical tasks, like moving 200 pound dummies off the battlefield or from the turret of a “damaged” vehicle. Peer assessments were also mixed.

Lance Cpl. Chris Augello, a reservist who prior to the experiment was pro-integration, submitted a 13-page essay—which he shared with the Marine Corps Times—on why he had changed his mind.  “The female variable in this social experiment has wrought a fundamental change in the way male [non-commissioned officers] think, act and lead,” he wrote, referring to the female presence and its effect on how Marine Corps small-unit leaders do their job.

Augello, according to the report, also noted that relationships between the female and male Marines in his platoon sometimes turned romantic and in turn became a distraction. Integration, Augello wrote, is “a change that is sadly for the worse, not the better.”

Though the experiment is the first of its kind, women have been serving in roles that have brought them close to or into combat over the past 15 years during two wars. The Marine Corps used Female Engagement Teams or FETs extensively in Afghanistan and Iraq to interact with the women in both countries.

Another issue was training. Female marines received different training from their male infantry counterparts, and so there was a gap in their preparedness, according to the Marine Corps Times report.

While a majority of the women dropped from the program, some men did as well. According to the Marine Corps Times, one platoon dropped 10 men and two women, while another report in the San Diego Union-Tribune noted that 13 men had dropped from a gender integrated company.  Though according to the Union-Tribune, 12 of them left for personal reasons not due to injury.

In the end, though, male members of the task force pointed out a number of women that impressed them. And the two women who stayed until the experiment’s conclusion told the Marine Corps Time they had found their true calling as infantrywomen.

“Every time a female would drop, it motivated the crap out of me to stay there,” Lance Cpl. Callahan Brown, one of the two final women to remain in the task force, told the Marine Corps Times. “Only 7 percent [of Marines are female] and so few even wanted to be in the infantry, and that’s all I want, is to be with grunts.”