That changed for her in 2003 amid a war without front lines. She says she's glad the military is changing its tune.
"It sounds like they are preparing women better now," she says.
IOC is a 12-week course that teaches new officers to be infantry platoon commanders and to "learn the basic skills in an ever-changing environment of physical and mental fatigue and high degree of uncertainty," says Col. Sean Gibson, a Marine Corps spokesman.
The course includes extended day and night marches and runs while carrying heavy loads. Throughout the process, the officers conduct continual "fire and maneuver" exercises in all kinds of conditions.
"Short answer: Teach Marine infantry officers to lead their Marines to succeed anytime, anywhere, in any situation," Gibson says.
Those who have graduated from IOC are reluctant to talk about the specifics of the course, crediting valuable battlefield lessons they learned from the uncertainty they faced in training.
The Brookings Institution's Michael O'Hanlon was able to witness the two women who tried out for the course. He described what it was like in a piece he wrote for the Wall Street Journal.
"This isn't the place where future Marine leaders learn of the accomplishments of past military greats or the ins and outs of Afghan culture," he wrote. "It is where, at 2 a.m., after marching all evening through a drenching downpour with 100 pounds of gear on their backs and no foreknowledge of when the exercise will end, Marines might stage a mock ambush of an enemy, or figure out how to evacuate a wounded comrade, or navigate through deep woods after their GPS devices are switched off by instructors."
The ability to complete these exercises is essential for those who would command other Marines to prove they can survive and lead in an intense combat environment.
In other service branches, advanced infantry training is also considered a key element to career advancement. Many senior Army officers bear the yellow and black Ranger Tab, denoting graduation from Ranger School, which boasts a 50 percent dropout rate.
This is not the case in the Marine Corps, according to the research plan.
"A recent RAND Corp. study (cited in the DoD report to Congress), found no statistical differences in the career progression of female officers in open MOSs (with closed positions) as compared to women in fully open occupations," according to the Marine Corps report. "Both groups of women shared the same likelihood of reaching pay grade of [colonel]."
New precedent shows this even playing field could continue past past that rank. The current Commandant of the Marine Corps Gen. James F. Amos is a fighter pilot. This billet is currently available to women in the Navy, but female Marines are restricted to flying transports. Amos' varied training never included advanced infantry school.
Even if the two women had passed IOC this fall, they would not have become infantry officers for ground combat units, which are still closed to women. Rather, they would take these skills on to the jobs they were already assigned.
But this is an ongoing process for the Marine Corps, which will continue to study the two female officers' performance.
"Because the performance capabilities of females at IOC is unknown, Training and Education Command will collect data in order to assess female participants and their performance against the IOC program of instructional standards," according to the Marine Corps report.
The Pentagon says there are no plans to alter the IOC physical requirements to accommodate women.
There are no women signed up for the next IOC class to begin in January. The next one will likely begin in March or later.
Paul D. Shinkman is a national security reporter for U.S. News & World Report. You can follow him on Twitter or reach him at email@example.com