Charles A. Robertson was born in Richmond, California, on August 1, 1912, the son of Charles Robertson and Florence E. Flavin and grandson of John T. and Mary F. Flavin. He lived in Albany, California, in the early 1940s. On August 17, 1943, he was inducted into the United States Army, and he trained at the Presidio of Monterey (Monterey, California); Camp Lee, Virginia; Fort Washington, Maryland; and Fort Omaha, Nebraska. Around July 1944, he was sent to Europe, where he served with the 48th Machine Records Unit (Mobile), 29th Machine Records Unit (Mobile), and 65th Machine Records Unit (Fixed) in England, France, Germany, and Belgium until returning home around March 1945. He attained the rank of corporal during the war. While overseas, Robertson was engaged to Naomi M. Watson ("Dee") of Oakland, California; they apparently broke off their engagement after February 1946. After his return to California, Robertson lived in Berkeley and Richmond.