Grace Hopper taught mathematics at Vassar but
joined the US Navy during WW2 to help develop computers for gunnery
calculations. She developed the first
compiler, which translated written language into computer code—a
breakthrough
that paved the way for user-friendly programming languages. Her efforts
led to
the creation of COBOL, one of the first widely used high-level
programming languages.
The Navy never really figured out what to do with her, so she fluctuated between active service and reserve duty, being skipped over for regular promotions, but she had finally achieved the rank of rear admiral by the time she retired in 1986.