Considered an above average officer, he was earmarked for early promotion during the interwar period and by 1938, commanded the destroyer HMCS Skeena.

During his time in command of Enterprise, he took part in the Battle of the Bay of Biscay, earning his Distinguished Service Order, the invasion of Normandy and bombardment of Cherbourg where he was wounded.

Grant succeeded Reid as Chief of the Naval Staff on September 1, 1947, and was made vice admiral.

[1] During the First World War, Grant was sent to the British Royal Navy for further training and was a midshipman with HMS Leviathan in February 1917.

It was during this period that the Chief of the Naval Staff, Percy W. Nelles rebuked Grant, having thought his promotion had gone to his head and earned a reprimand for poor behaviour.

Grant was then sent east where he appointed Captain (D) in St. John's in command of the destroyers assigned to the Newfoundland Escort Force.

On December 28, 1943, in the Bay of Biscay, Enterprise and fellow light cruiser, HMS Glasgow took on 11 German destroyers.

He was awarded the Bronze Star Medal by the United States for his actions during the naval bombardment of Cherbourg on June 25, 1944, during which he was wounded in an exchange with shore batteries.

After leaving Enterprise, Grant returned to Royal Canadian Navy service and commissioned the cruiser HMCS Ontario and deployed to the Pacific.

However, the surrender of Japan ended the war before Ontario could arrive and instead Grant and the cruiser helped re-establish British control over Hong Kong.

[2][6] Grant was promoted rear admiral in February 1946 and was appointed Chief of Administration Services and Supply in Ottawa, Ontario.

"[9] By the time of Grant's promotion to vice admiral, appointment as the Chief of the Naval Staff and successor to Reid on September 1, 1947, the Minister of National Defence, Brooke Claxton sought to focus the navy's efforts on anti-submarine warfare (ASW) defence.

However, he disapproved of Claxton's interference in naval affairs and some of these, including the re-arrangement of ranks within Canada's armed forces was one of the factors that led to a series of personnel unrest incidents in 1949.

The Korean War allowed Grant to seek funds for naval expansion and seven of the St. Laurents were authorised, along with increased personnel and active ships.

The launch of St. Laurent established Canada's naval identity for the remainder of the Cold War as an ASW-specialised force.