More than 3,500 service members received the Medal of Honor since its establishment. But in its 160-year history, only one woman was honored: Mary Edwards Walker, M.D.

Walker was one of the few practicing female doctors at the time and arrived in Washington, D.C., seeking to join the U.S. Army as a  surgeon. The Army refused Walker, stating that, “Women didn’t belong in the Army.”

Despite this setback, Walker pursued her goal and volunteered her services to many Washington-based hospitals until she found a doctor that accepted her proposition and allowed her to work as a surgeon.