On September 13, 1954, Grace Hopper reported to the Navy's Bureau of Ships in Washington, D.C., to take a position as a civilian programmer. She had been working on computing systems since 1944, when she joined the Bureau of Ordnance Computation Project at Harvard and began programming the Mark I — a 51-foot electromechanical computer that filled a large room and had to be manually threaded with paper tape.

Hopper was born in 1906 in New York City, graduated from Vassar, earned a PhD in mathematics from Yale in 1934 — one of the few women to hold a mathematics doctorate from Yale at the time — and was teaching at Vassar when she joined the Navy in 1943. She was thirty-seven and too old, by regulation, to be commissioned; she petitioned for a waiver. It was granted.

At Harvard she worked under Howard Aiken, who ran the Mark I project. She was the third programmer. When Aiken published accounts of the Mark I's development, he credited the male engineers by name. Hopper and the other women programmers appeared in group photographs.

Her most consequential work came later: she developed the first compiler — a program that translates human-readable code into machine language — which made programming accessible to people who were not mathematicians. COBOL, the business-computing language that still runs substantial portions of the world's financial infrastructure, was built on her framework.

She retired from the Navy as a rear admiral at seventy-nine, the oldest officer on active duty. She was awarded the Presidential Medal of Freedom posthumously in 2016.