John Sheldon Doud Eisenhower was born in Denver in 1922 to Dwight D. Eisenhower and his wife, Mamie. He was an assistant staff secretary in the White House during the last few years of his father's administration, and served as U.S. ambassador to Belgium during the Nixon administration. Both father and son graduated from the U.S. Military Academy at West Point, the son on June 6, 1944 — the day his father oversaw the Allied invasion of Europe. He spent 35 years in the Army, including 19 years on active duty and several years in the Reserve. He retired with the rank of brigadier general. Eisenhower was the author of numerous books about military history. Eisenhower taught English for three years at West Point, then volunteered for service during the Korean War. He is survived by his second wife, Joanne, son David and daughters Anne, Susan and Mary. David married President Richard Nixon's daughter Julie.