The term DDE Predecessor refers to the three presidents who preceded Dwight D. Eisenhower, namely: Ike (3 letters), Mamie (5 letters) and HST (3 letters). Ike was the nickname of President Dwight D. Eisenhower, who served from 1953 to 1961. Mamie was the nickname of President Harry S. Truman, who served from 1945 to 1953. HST was the nickname of President Herbert Hoover, who served from 1929 to 1933.