In all of American history, only one woman has been awarded the Medal of Honor — and Congress tried to take it back.

Her name was Mary Edwards Walker, and she was a doctor at a time when female physicians were rare. She graduated from the Syracuse Medical College, and at the outbreak of the Civil War traveled to Washington with the intention of joining the Army as a medical officer. When she was rejected, she volunteered as a surgeon and served in that capacity for various units through the war years, continually agitating for a commission.

Walker was captured by the Confederate Army in April 1864 and held for a few months at Castle Thunder prison near Richmond, Va. Finally, that October, she was given a commission as acting assistant surgeon, the first female physician in the U.S. Army.

President Andrew Johnson signed a bill awarding Walker the Medal of Honor in 1865, because she "has devoted herself with much patriotic zeal to the sick and wounded soldiers, both in the field and hospitals, to the detriment of her own health, and has also endured hardships as a prisoner of war."

She continued to practice medicine after the war, and took up the cause of women's rights with a passion. Walker had long preferred to wear men's clothing, and was even arrested several times for "masquerading" as a man.

In 1917, Congress changed the criteria for awarding the Medal of Honor, restricting it to those who had engaged in actual combat with an enemy. Hundreds of medals, including Walker's, were rescinded. She refused to return hers, however, and wore it proudly until her death in 1919.

Fifty-eight years later, President Jimmy Carter reinstated Walker's Medal of Honor, recognizing her "distinguished gallantry, self-sacrifice, patriotism, dedication and unflinching loyalty to her country, despite the apparent discrimination because of her sex."

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