A lengthy experiment studying women during combat skills tests found that all-male units performed better than mixed-gender ones in most tactical areas and that women suffered more injuries than men, the Marine Corps reported this week.
One measure showed that the musculoskeletal injury rate for women was 40.5%, compared with 18.8% for men.
The report, however, drew swift criticism from leaders who support opening military combat roles to women. On Friday, Navy Secretary Ray Mabus, the civilian head of the Navy and Marine Corps, told National Public Radio that the Marines had used flawed methodology in designing the study and exhibited prejudicial thinking about certain results from the testing.
The Marine Corps started the experimental mixed-gender task force last fall at Camp Lejeune, N.C., and later at Twentynine Palms and other California bases to help the commandant decide whether women should be accepted into ground combat specialties now closed to them — including the infantry, artillery and tanks.
The task force began operations last October with about 600 Marines, including staff. Numbers dwindled significantly during the grueling 10-month training and testing regimen, particularly among the women who were serving for the first time in a ground combat specialty, since most primary war-fighting jobs are closed to women outside of research purposes.
The infantry company and its two platoons, including a provisional one of Marines who had not attended the introductory course, were hit especially hard by injuries. In its research summary, the Marine Corps concluded that the "well-documented comparative disadvantage in upper and lower-body strength resulted in higher fatigue levels of most women, which contributed to greater [incidence] of overuse injuries such as stress fractures."
Gen. Joseph F. Dunford Jr., outgoing Marine Corps commandant and the next chairman of the Joint Chiefs of Staff, has not decided whether to ask for an exception to the new Department of Defense policy opening all military jobs to women by Jan. 1, according to a Marine official with knowledge of the proceedings. The Joint Chiefs chairman and Defense Secretary Ashton Carter will have the final say after reviewing the research required of any service seeking an exception.
By releasing its research, the Marine Corps is vetting conclusions with the public before a final decision is made.
Leaders from the Army, the Navy and U.S. Special Operations Command have indicated in public comments that they are unlikely to fight the new policy. The Air Force has already opened all jobs to women among its conventional forces.
Mabus has said that he wants Marine infantry and special operations jobs to open to women and that he does not intend to seek any exceptions.
The primary consideration in conducting the research was combat effectiveness, followed by the health and welfare of individual Marines, the report says. It quotes from a 1992 presidential commission concluding that "risking the lives of a military unit in combat to provide career opportunities or accommodate the personal desires or interests of an individual, or group … is more than bad military judgment. It is morally wrong."
The summary of findings makes no mention of top performers among the women on the task force who may have met or exceeded the male average. Instead, the report said it focused on overall performance by female troops — who are limited on average by smaller stature and other physiological differences, historical restrictions on access to combat training, and cultural factors such as gun use.
Among the findings:
All-male units performed better than mixed-gender units on 93 of 134 tasks, or 69%; gender-integrated units performed better than all-male units on two tasks, which were not identified.
All-male infantry squads were faster in each tactical movement, with differences more pronounced when "crew-served" weapons such as machine guns had to be carried in addition to the standard assault load.
All-male infantry rifleman squads were more accurate shots, with notable differences in all weapons except the M4 rifle.
Men in the provisional infantry platoon who had not attended the infantry course were more accurate marksmen than women who had, hitting 44% of targets with the M4 rifle versus 28% among women trained at the infantry school.
All-male squads were notably better as a group when tackling obstacles and evacuating casualties. For example: "When negotiating the wall obstacle, male Marines threw their packs to the top of the wall, whereas female Marines required regular assistance in getting their packs to the top."
Two primary factors are associated with successful movement carrying heavy loads — lean body mass and peak oxygen uptake. Women scored lower in both areas. The men had an average of 20% body fat, compared with 24% among women. Women had an average of 10% lower peak oxygen uptake than men.
Advocates for expanded roles for women in combat reacted strongly to the findings, questioning the purpose and methodology of the research.
"The limited report is a skewed attempt to set the stage for the Corps to request exceptions to the Department of Defense's mandate for full combat integration," and a futile attempt to stop the "inevitable" opening of all military jobs to women, Judy Patterson, chief executive of the Service Women's Action Network, said in a statement.
Retired Army Col. Ellen Haring, program director of the Combat Integration Initiative at Women in International Security, took issue with the Corps' decision to highlight average performance. "They've aggregated data on an average basis, and said therefore all women are forbidden because the average woman can't do it.
"The deck has been stacked against these women," she added. "The whole ground task force was skewed in that these women were brand-new to these specialties. They didn't have the conditioning or the right equipment in many cases." In light of that, it is no surprise that seasoned men outperformed them, Haring said.
Megan MacKenzie, author of "Beyond the Band of Brothers: The U.S. Military and the Myth that Women Can't Fight," released in June by Cambridge University Press, concurred. "It is disappointing that the Marines' limited study is overpowering years of research. To me this shows that integration takes time and significant adaptations to training. A single one-off study would not pass any rigor in any other scientific context," she said.
Previous studies by Canada, Denmark and the U.S. have found that women can perform as well as men in combat roles, and a study by the Israel Defense Forces determined that the performance gap between genders can be reduced by recruiting physically fit women, developing prep courses for basic training and assigning personnel based on mission needs independent of gender, said MacKenzie, a senior lecturer at the University of Sydney in Australia who also wrote a book on female soldiers in Sierra Leone's civil war.
Many Marine infantrymen and combat veterans, meanwhile, are critical of the push for gender integration, saying it puts gender politics before combat readiness.
Retired Marine Capt. Stanton Lee is a former civilian police officer, Marine infantry officer and enlisted Marine who served in Afghanistan. He has experience in mixed-gender units as well as all-male ones.
"Yes, we can find that minority percentage of women who can hike 100-pound loads and even pass [Army] Ranger School, but how much resource will it take to screen them and will it be cost and time-effective?" Lee asked. "How will all of this add to the effectiveness of the Corps as a war-fighting institution, or would we do it so we can pat ourselves on the back to say how tolerant we've become?"
Rep. Duncan Hunter (R-Alpine), a former Marine artillery officer and combat veteran, said in a statement released through his spokesman: "The effectiveness of Marine Corps ground combat units shouldn't hinge on politically motivated decision makers.
"This is a process that should be influenced by Marines only and this newest report underscores why they may have reservations and why a decision can't be rushed for political expediency."