Clarke's first jobs were as a secretary and defense worker before she turned twenty-one. On August 10, 1945, at the age of 21, she enlisted in the Women's Army Corps just before World War II ended. Clarke was expecting to serve until the war ended, plus a few additional months. A male commander stated that it was unlikely she would even make it through the officers training program. Clarke then decided to stay and made it through the initial training, served in the enlisted ranks for four years and was commissioned a second lieutenant in 1949. She went on to serve for 36 years making a career of the U.S. Army and the woman that has served the longest in the military. Most of this time she spent in the Women's Army Corps. Clarke did her basic training at Fort Des Moines Provisional Army Officer Training School in Iowa. Upon completion of basic training she was then immediately assigned to being a supply sergeant at Camp Stoneman, California. Her next assignment was in 1948 at Berlin, Germany. While in Berlin she was in the middle of the Berlin Airlift crisis. She then served at the U.S. Army Chemical Center and Valley Forge General Hospital. Clarke then recruited for a year. Clarke attended the WAC Officer Candidate School at Camp Lee and after the schooling she became a WAC commissioned officer as a second lieutenant on September 29, 1949. Then she served two years at a WAC unit as a commanding officer in Tokyo before going back to the United States. Clarke then held several officer's positions from 1958 through 1971 in Texas, Alabama, Maryland, California and Washington, D.C. In Washington, D.C., she worked at the Office of Equal Opportunity and Deputy Chief of Staff for Personnel. She also did WAC training and advisement. Clarke was promoted to colonel in 1972 to become the commander of the U.S. WAC Center and School in Fort McClellan. In 1974 she was the chief of the WAC Advisory Office. On 1 August 1975, Clarke became brigadier general and served as the final director of the WAC. In 1976 she had special courses at the U.S. Military Academy Preparatory School to prepare women to attend military academies, since women were then allowed to attend by an executive order of President Gerald Ford. Clarke was the last director of the WAC until it was dissolved at the end of her tenure in 1978. After this assignment she was given the rank of a two-star general and promoted to major general in June 1978. She then immediately became commander of the U.S. Army Military Police School and Training Center upon leaving the WAC and during her tenure, oversaw the return of the U.S. Army Chemical School in 1979 to its former home. Now with three major missions, a basic Training Brigade, the Army Military Police School and the Army Chemical School, she became commander of The U.S. Army Military Police and Chemical Schools, Training Center, Fort McClellan, Alabama. It was the first time a woman commanded a major Army post. Clarke was the first woman to achieve the rank of major general in the U.S. Army.
