Harry S. Truman 33rd President, Senator and Vice President before he succeeded to the presidency upon the death of Franklin D. Roosevelt. Truman is the only President to have served in action in World War I. President during the final months of World War II, he approved the plan to drop atomic bombs on Hiroshima and Nagasaki. He was re-elected in 1948 and presided over America as it sought its path after the war and tensions with the Soviet Union increased, marking the start of the Cold War. Here is a signed Presidential Christmas Card by President Harry Truman.