Admiral Knoll’s strength was as a staff officer. The list of individuals on whose staffs he served: Admiral Thomas C. Hart, Admiral Ernest J. King, Ambassador Averell Harriman, Admiral Richmond Kelly Turner, Rear Admiral Walter F. Boone, Vice Admiral Arthur D. Struble, Admiral Arleigh A. Burke, Vice Admiral Alfred M. Pride, Vice Admiral Stuart H. Ingersoll, Vice Admiral Wallace M. Beakley, Vice Admiral Glynn R. Donaho, and Admiral Robert L. Dennison. Knoll graduated from the Naval Academy in 1930. He served 1930–32 in the battleship Texas (BB-35), sandwiched around unsuccessful flight training at Pensacola in 1931. In 1932–34 he served on board the destroyers Southard (DD-207) and Preble (DD-345). After participating in a Navy geographical survey of the Aleutian Islands in 1934, he served in the battleship Oklahoma (BB-37), 1934–36, then took a three-month course in chemical warfare at Edgewood Arsenal in 1936. He was a student at the Navy’s Postgraduate School, 1936–38, then received a master’s degree in aerology from the Massachusetts Institute of Technology in 1939. In 1939–40 Knoll served with Patrol Wing Five. He had an extended period on the staff of Commander in Chief Asiatic Fleet, 1940–42, and was evacuated from Corregidor just before it fell to the Japanese in May 1942. He was stationed in Washington, 1942–44 on the CominCh staff, officer in charge of the weather central, and assistant secretary, Joint Chiefs of Staff. In 1944–45 was on the staff of the U.S. ambassador to the Soviet Union to facilitate implementation of Lend-Lease and agreements at the Tehran Conference. In 1946 Knoll was part of the U.S. military delegation to organizing meetings for the United Nations. He commanded the oiler Severn (AO-61), 1946–47, before service in the strategic planning section of OpNav, 1948-52. He commanded the attack transport Menard (APA-201) in 1952 before returning to service in the strategic planning section of OpNav. In 1955 Knoll was commanding officer of the light cruiser Roanoke (CL-145) and from 1955 to 1957 was chief of staff to Commander Seventh Fleet. From 1957 to 1959 he served in the OpNav fleet maintenance division and as chairman of the Ship Characteristics Board. In 1959–60 he was Commander Destroyer Flotilla Four. In 1960-61 was director of the OpNav Technical Studies Group before duty in 1961–63 as Commander Service Force Atlantic Fleet, part of it during the Cuban Missile Crisis. From 1963 to 1965 Knoll was Oceanographer of the Navy, and his final active duty, from 1965 to 1967, was as Deputy Commander of the Military Sea Transportation Service. Post-retirement activities included employment by Litton Industries.