Gen. Knowlton, a graduate of West Point in January 1943, was the 49th superintendent of the academy, a post he held from 1970 to 1974. At the time, he was the longest-serving superintendent since World War II. He also served on the staffs of Gen. Dwight D. Eisenhower and Gen. Omar Bradley at the Supreme Headquarters Allied Powers Europe of the North Atlantic Treaty Organization in the early 1950s. He was on the general staff of the secretary of Army for two years until he went to West Point, where his daughter Hollister met and married Lt. David Petraeus, now a four-star general and commander of the multinational forces in Iraq. Gen. Knowlton also taught social sciences at West Point while working on a master's degree in political science at Columbia University, which he received in 1957. He also graduated from the U.S. Army Command and General Staff College and the National War College. he was a senior fellow at a defense studies institute at the National Defense University at Fort McNair for 15 years. He also served as an adviser for the Defense Nuclear Agency and was a member of the Defense Intelligence Agency Science and Technology Advisory Board. In the private sector, he became a director of the Chubb Corp. and served as a trustee for Davis and Elkins College in West Virginia.In addition to his daughter, of Fort Myer, survivors include his wife of 64 years, Marjorie D. "Peggy" Knowlton of Alexandria; three sons, retired Army Lt. Col. William A. Knowlton Jr. of Burke, Davis D. Knowlton of Manila and Timothy R. Knowlton of Mill Valley, Calif.