In the fall, two freshly minted female lieutenants joined about 100 men in Quantico, Va., for one of the most grueling experiences that soldiers not in war can experience: the Marine Corps' Infantry Officer Course.
At the 86-day course, candidates haul heavy packs and even heavier weapons up and down steep hills, execute ambushes and endure bitter cold, hunger and exhaustion. Uncertainty abounds: They do not know their next task, or even how long they will have to perform it. At IOC, calm leadership under duress is more important than physical strength, although strength is essential.
One of the women -- the first to enter the course -- was dropped on the first day, with about two dozen men, during a notoriously strenuous endurance test. But the second woman lasted deep into the second week, when a stress fracture in her leg forced her to quit.
"She was tough," Gen. James F. Amos, the Marine Corps commandant, said of the woman, who is now at flight school. "She wasn't going to quit."
Gen. Amos hopes the experiences of those women, and others to come, will provide crucial clues about the future of women in the infantry, a possibility allowed by the recent lifting of the 1994 ban on women in direct combat units.
For the Marine Corps, probably more than any other military service, gender integration is a difficult affair. Not only is the corps the most male of the services, with women making up only about 7 percent of its ranks, but it is also a bastion of the infantry. Nearly 1 in 5 Marines are "grunts," proud of their iconic history of bloody ground battles, from Belleau Wood to Iwo Jima to Chosin Reservoir to Fallujah.
Not surprisingly, the idea of women in the infantry draws sharp questions from many active-duty Marines and veterans, who express concerns that standards will be diluted for women.
In an interview, Gen. Amos acknowledged hearing those worries, and insisted that the corps would not lower its standards. To guarantee that, he plans to use the course, which Marines consider the gold standard of infantry training, to study the performance of potential female infantry officers, and then use that data to develop requirements for enlisted infantry Marines.
In March, two Naval Academy graduates will become the second set of women to enter the course. Over the coming years, Gen. Amos is counting on dozens more female volunteers to provide him with enough information to decide whether women can make it in the infantry. The outcome, he says, is far from certain.
"I think there is absolutely no reason to think our females can't be tankers, or be amtrackers, or be artillery Marines," he said, referring to tracked amphibious assault vehicles. "The infantry is different."
Indeed, Gen. Amos said, if too few women are able, or willing, to join the infantry, he or his successor may ask the defense secretary to keep the infantry closed to women. The deadline for that request is January 2016.
"You could reach the point where you say, 'It's not worth it,' " Gen. Amos said. "The numbers are so infinitesimally small, it's not worth it."
Advocates for women in the military would almost certainly protest any effort to keep the Marines infantry male-only. Those advocates acknowledge the harshness of infantry life: carrying heavy loads on foot for long distances and enduring spartan environments are requisite. But they say that properly trained women will make it through IOC and, eventually, whatever program the corps creates for screening and training enlisted infantrywomen.
Even if very few women pass IOC, enlisted women should still be allowed to join male-led infantry units, said Greg Jacob, a former Marine officer who is the policy director for the Service Women's Action Network, an advocacy group.
"Leadership is leadership," Mr, Jacob said. "You don't need a female leader to lead female Marines."
Gen. Amos, a fighter pilot, opposes doing that, saying enlisted female Marines will do best if they have female officers as mentors. "I'm not going to bring in 18-year-old females and put them in an infantry battalion when I've got no female officers," he said. "I can't do that."
In the coming months, the most pressing task for all of the armed services will be establishing gender-neutral requirements for every combat job, known as military occupational specialties. Of the 340 job categories in the Marine Corps, 32 had been closed to women under the 1994 ban.
The Marine Corps has set out a two-tiered process for creating those requirements: one short-term for armor, artillery, combat engineering and low-altitude air defense units, and a longer-term one for the infantry.
For noninfantry combat units, Marine commanders will be expected to establish requirements for every job by June. For example, artillery crews, working in pairs, must be able to lift and load shells weighing about 100 pounds. Tank crew members must be able to lift 40-pound shells using arm strength alone, because of the vehicle's tight quarters.
Those requirements will become the basis for physical tests intended to screen men and women for particular jobs. It is possible that the tests already administered to all Marines annually -- the physical fitness test and the combat fitness test -- will be deemed adequate for determining physical ability for some jobs. But where those tests are not adequate, the corps will develop additional ones.
The corps will also begin using a new physical fitness test in January that will require all Marines, male and female, to do a minimum of three pull-ups, and, for Marines younger than 27, 50 crunches in two minutes. The three-mile run time will be scored by gender.
Marine officials say the 15 women who volunteered to use the new fitness test this year -- it is not required until next year -- all passed with maximum scores for pull-ups, doing eight or more. For men, 20 pull-ups are needed for a maximum score.
Gen. Amos said he hoped tests for the noninfantry combat units would be in place by the end of this year, potentially allowing women who are finishing boot camp early next year to move into some combat units.
"I'm really pretty bullish on this thing," he said.
The infantry will take longer. The Marine Corps produces only about 110 female officers a year, and so far, only four have volunteered for IOC. Gen. Amos said he would need many more volunteers to draw conclusions.
Given the heavy dose of infantry life that all officers experience in their initial training, he said he was unsurprised that women were not knocking down the door to enter IOC.
"By the time you've spent six months of this, picking ticks off of every part of your body, freezing cold, smelling like a goat and eating MREs, you may go, 'Well, this infantry stuff isn't for me,'" he said, referring to packaged military meals. "So we don't have a lot of volunteers."nation