It's true. Uncle Sam wants you. But does he want all of us or just half of us?

You probably know that women can serve in all four branches of the United States Armed Services. That's been true since soon after World War II. Today, women make up about 14% of active military personnel, and more than 10% of these women are sent to war zones.

Where and how military women should serve remains highly controversial, however. Throughout US history, women have been assigned practically every military role except direct combat. And since they weren't allowed to fight in combat, they could not serve as officers who supervise combat missions either.

What you may not know is that women have been part of the country's war efforts since the Revolutionary War, and they served in combat roles even then. These women took tremendous risks to serve their country, and their efforts, in part, have led to the progress we've seen toward the equal treatment of women in the US military now.

At the beginning of this country's history, no one even considered that women might serve as actual soldiers in military missions. During the American Revolutionary War, women mostly filled conventional roles-- cooking, washing clothes, and nursing wounded soldiers. They were called camp followers, and they were given food rations along with the men in the camps.

The most famous camp follower was Molly Pitcher, who, according to legend, stepped in to fill her husband's place loading a cannon after he collapsed or was wounded. Molly Pitcher was probably a nickname given to a woman named Mary Hays, who was one of the camp followers led by Martha Washington. The nickname may relate to one of the duties performed by camp followers-- delivering fresh water to the troops during battles.

Some women did fight as soldiers at the beginning of this country's history, though, disguised as men. Back then, military service did not require extensive physicals the way they do now. Women could pass as male soldiers just by cutting their hair, padding their pant's waist, and binding their chests.

One such woman was Deborah Sampson. She served more than a year and a half in the Continental Army using her deceased brother's name and was honorably discharged under her male identity.

The practice of passing as male continued in the Civil War. Sarah Edmonds fought disguised as Franklin Flint Thompson. As part of the Union Army, Edmonds delivered mail and messages and worked as a nurse. She deserted in 1863 after contracting malaria, fearing her sex would be discovered if she were hospitalized.

Cathay Williams was the first African-American woman to enlist and the only documented to serve in the United States Army posing as a man under the pseudonym William Cathay.

Women served in less official capacities as well during the Civil War. Harriet Tubman, who is known more for her work on the Underground Railroad, organized and led groups of Union scouts for US General Rufus Saxton in South Carolina.

In later American wars, physical exams were required for enlistment in any of the armed forces, so women who wanted to serve in combat roles were unable to pass as men. Still as early as World War I, women contributed in ways that had seemed unthinkable in earlier years, performing manufacturing and clerical tasks that had previously been reserved for male workers.

In World War I, military leaders realized that if women were trained to perform the less dangerous home-front tasks that had been performed by men during more peaceful times, the armed forces could send more men into combat as women took their places at home.

In March of 1917, the Navy began recruiting women into the Naval Coast Defense Reserve to serve as radio operators, nurses, messengers, drivers, and in several other roles. Though the female yeoman were officially part of the Navy, the Navy did not have the facilities to house them in separate quarters. So unlike male enlistees, they had to find their own housing and buy or make their own uniforms.

Shortly after World War I ended, the program allowing women to enlist and serve was dismantled, and female yeoman had to take civilian jobs if they wished to continue working for the Navy.

During World War II, all branches of the armed forces opened enlistment to women, though female recruits had to serve in the reserves or in special auxiliary groups. For instance, the Women Airforce Service Pilots, or WASP, remained a separate entity throughout the war with separate funding, command structures, and training facilities. They received similar flight training and flew similar support missions.

As during World War I, the stated purpose of allowing women to serve in military positions during wartime was to free up more men to fight on the front lines as infantry. Women also entered the general workforce in large numbers, taking on all kinds of jobs previously done only by men, such as weapons and equipment manufacturing and railroad work.

While women still were not permitted to participate in armed conflict, their duties often brought them close to the front lines. Usually, these overseas' roles were related to nursing, but the Army Signal Corps trained at least 230 women for work as phone and radio operators and sent some to Europe to perform their roles.

The women in the Signal Corps wore US Army uniforms and insignia, but when the war was over, the Army claimed that they had never been members of the service. Congress finally granted them retroactive military status in 1979.

The women's naval service also began once again to recruit and train women for wartime duties during World War II. The program was called WAVES, which stood for Women Accepted for Voluntary Emergency Service. As part of the WAVES program, thousands of women were trained in military drills as well as food conservation, land telegraphy, the manufacturing of surgical dressings and bandages, and signal work.

Once assigned to a location, WAVES took positions in aviation, medicine, communications, intelligence, and science and technology. Their participation in the Navy was much more varied and integrated than the other service branches.

But the WAVES, like other special efforts to include women in military service, were discontinued after the war ended. Then in 1948, the Women's Armed Services Integration Act removed the legal barriers to women enlisting in the regular branches of the United States military.

The United States Coast Guard had a women's auxiliary branch as well nicknamed SPARS, which was a contraction based on the Coast Guard's motto, semper paratus, and its English translation, "always ready."

In the 1950s, more than 500 women served as nurses in combat zones in Korea, most of them involuntarily recalled after serving in the Army Reserves. The Korean War was the first to place US women this close to the front lines. During this time, Pilot Captain Lillian Kinkella Keil flew 250 evacuation missions, many of them across the Atlantic from Korea.

In the 1970s during the Vietnam War, many enlistment requirements for women were changed. Women could enlist at the same ages as men and for similar amounts of time, but they could not fight in direct combat roles.

Still, as many as 10,000 women worked alongside men on the front lines in support in medical roles. At the same time, most military leaders believed that women were biologically and psychologically unsuited for direct combat missions, though they were able to prove their fitness for stressful roles in the midst of combat.

In 1983, the US Coast Guard established a new policy on women in combat, noting that men and women on Coast Guard ships are trained and work as a team and that removal of women from the team if a ship encounters combat would have serious negative consequences for the mission and for everyone involved.

Over the next 30 years, women flew combat missions, commanded ground invasions, and worked on teams that encountered combat. Taken together, their experiences raise questions about both the fairness and the necessity of bans on direct combat missions for female soldiers.

In 2013, the Pentagon signed an order that opened ground combat military positions to women, acknowledging that the lines between combat roles and support roles have become blurred and that women were, in fact, already in combat on many fronts.

Throughout the history of our country. American women have shown their willingness to support war efforts and to serve in the military, including in positions that place them in combat situations. As progress continues for women in the armed services, it is likely they will eventually be allowed to serve in elite special operations units, including the Army's Delta Force and the Navy SEALs.

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