In 1925, Admiral Henry Thomas Mayo, who had been the commander-in-chief of the Atlantic Fleet in 1918, said: "The Navy and our country owe to Captain Belknap a debt which can hardly be over-estimated; for it was the knowledge and experience acquired and the doctrine and methods established in the Mine Force under command of Commander [sic] Belknap that enabled the Navy to, first, fit out improvised by very efficient minelaying vessels and, second, to operate them under war conditions in a manner which brought commendation from all." From 17 March to 11 April 1919, Belknap was the third of three officers to serve as Acting President of the Naval War College while the colleges academic activities were shut down for World War I and its immediate aftermath. In 1919 and 1920 he was commanding officer of Destroyer Submarine Base Squantum at Squantum, Massachusetts. He then returned to the Naval War College as the chairman of its Strategy Department from 1921 to 1923. Upon the commissioning of the new battleship on 30 August 1923, he became her first commanding officer. Relinquishing command of "Colorado" in 1925, Belknap became commanding officer of the receiving ship at San Francisco, California. In 1926 he moved on to his final tour, in which he was commanding officer of Naval Training Station Norfolk in Norfolk, Virginia. Belknap was transferred to the retired list on 26 June 1926, but remained on active duty, and on 3 May 1927 was promoted to rear admiral by an act of the United States Congress for his World War I service. He relinquished command of the training station on 30 June 1927 and entered retirement. In 1919, Belknap received the Distinguished Service Medal for his achievements in the North Sea Mine Barrage effort the previous year. He also received the Spanish Campaign Medal, the World War I Victory Medal, and the Marine Corps Expeditionary Medal during his career. In 1920, Belgium made him an Officer of the Order of Leopold and France made him an Officer of the Legion of Honor. He received various medals for his 1909 relief work at Messina and Reggio di Calabria, including the American Red Cross Gold Medal. Belknap had a long and active retirement and was a member of many military orders and societies. He was elected a Hereditary Companion of the New York Commandery of the Military Order of the Loyal Legion of the United States on 17 November 1937 and served as the Orders national commander-in-chief from 15 October 1947 to 9 October 1951.