A member of the Blackfoot tribe, Spotted Wolf spent her childhood working on her father's ranch in Heart Butte, Montana, where she cut fence posts, drove trucks and broke horses. She first expressed an interest in joining the army when she was aged 18, shortly after the US entered into World War 2 at the end of 1941. However she was initially discouraged by a recruitment officer who told her that the war was 'not for women'.
Spotted Wolf was eventually accepted into the Marine Corps Women's Reserve in July 1943, making her the first Native American female Marine. She almost did not accept the post as her father was dying from a horse riding accident, however her mother and sister strongly encouraged her to pursue her ambitions. She underwent rigorous boot camp training at Camp Lejeune, during which she gained 15 pounds of weight from the diet and rigorous exercise. She later described the training as "hard, but not too hard" given her background on the ranch.
On completion of her training Spotted Wolf went on to serve 4 years in the Marines in California and Hawaii. She drove trucks loaded with heavy equipment, a job normally reserved for men, and also sometimes worked as a jeep driver for visiting generals. Spotted Wolf's career quickly gathered media attention and she was featured in numerous news stories, and even her own comic book, to promote the war effort.