The appointment predetermined his eventual appointment as rear-admiral RCN and director of the Naval Service of Canada upon the formation of the RCN on 4 May 1910. By 1914, at the beginning of World War I, the new navy's fleet consisted of two old cruisers and a collection of converted civilian and commercial vessels. Kingsmill was promoted to Admiral in 1917. He was made a knight bachelor in 1918. He was awarded for outstanding services as the Director of Naval Services of Canada 1910–1921. Kingsmill retired on 31 December 1921. He maintained a summer home on Grindstone Island, in Big Rideau Lake, near Portland, Ontario, where he loved to sail. His guests included the Duke of Devonshire, Governor General of Canada from 1916 to 1921; Sir William MacKenzie, railway entrepreneur; and Neville Chamberlain, later Prime Minister of Great Britain from 1937–1940. When he died at Grindstone Island on July 15, 1935, a ". . . huge flotilla of boats brought him in from the island. . ." He is buried in the Anglican cemetery in Portland, where an Ontario Heritage Trust plaque commemorates his contribution to Canadian naval history. Medals of Admiral Sir Charles Edmund Kingsmill, Kt:  Kingsmill and his wife, Constance, were prominent figures in Ottawa's social life. She was active in various causes, including as a supporter of birth control. They lived in a large stone house which they named "Ballybeg" on Crescent Road in Rockcliffe, which was designed for them during World War I by Montreal architect H. C. Stone. When the house was built, Rockcliffe was outside city limits, and raising chickens and cattle was permitted. Since 1970, the house has been occupied by Tunisia's ambassadors to Canada. Kingsmill's cousin, Colonel Walter Bernard Kingsmill, the son of Admiral Kingsmill's uncle, Nicol Kingsmill, was head of the 10th Royal Grenadiers and led the 123rd Battalion on the front lines in France during the First World War. His daughter Diana was an Olympic athlete and journalist, who married historian J. F. C. Wright. Kingsmill House is named for him. The junior officer quarters building at Venture NOTC, the Canadian Naval Officer Training Centre, is named after him.