Army Brig. Gen. Anna Mae Hays, the first female general in U.S. history, died Sunday at a retirement home in Washington, D.C., the Washington Post reports. Hays, who retired almost 50 years ago, was 97.

Hays had been in charge of the Army Nurse Corps before she retired. During her tenure, she had “persuaded the Army that nursing was important enough to spend money on ― a hard sell at that time,” a Army Office of Medical History historian told the Post.

She also advocated for changes that paved the way for women to serve in the military.

Hays first served in Burma, China and India during World War II and set up the first military hospital during the Korean War.