Following her grandfather’s footsteps, Hopper decided to enlist in the Navy at the beginning of World War II. However, she was rejected for various reasons, including her age (34), her height-weight ratio, and the Navy’s determination that her skills as a mathematician were not valuable to the war effort.
However, this did not stop Grace Hopper.
To serve her country, Hopper decided to join WAVES and the United States Nation Navy Reserve, and continued to do so until her retirement. In fact, Hopper retired at the age of 79, making her the oldest serving officer in the United States. She achieved the rank of Rear Admiral by the end of her career.