Cowan never went to school, but entered the Royal Navy in 1884 at the training ship,[1] HMS Britannia, a classmate to fellow future admiral David Beatty.

In June 1901 he was promoted commander at the early age of thirty, and in May the following year he was appointed to the battleship HMS Resolution, coast guard ship at Holyhead.

[1] Cowan's mission was to keep the sea lanes open to the new republics of Finland, Latvia, Estonia and Lithuania, which were under threat of being overrun by Soviet Russia.

During the course of this campaign, coastal motor boats attached to Cowan's command sank one Bolshevik battleship and a cruiser at Kronstadt naval base.

Andrew Browne Cunningham, later Britain's leading Second World War admiral, commanded Cowan's destroyers in this campaign.

Cowan's forceful diplomacy ensured a successful mission, for which he was advanced to Knight Commander of the Order of the Bath in 1919 and created a baronet, "of the Baltic", in the 1921 New Year Honours.

Cowan voluntarily took the lower rank of commander and went to Scotland in 1941 to train the newly formed corps in small boat handling.

8 (Guards) Commando involving an expedition along the North Egyptian and Cyrenaica coast aboard HMS Aphis, a river gun-boat from the China Station with a top speed of 12 knots.

The expeditions were repeatedly attacked from the air over several days by Axis forces before being constrained to abandon the endeavour on the second attempt through battle damage to the boat's rudder mechanism, which limited it to going around in circles in repetition.

During the incessant attacks, with scores of bombs splashing into the sea about the vessel, Cowan (believed by the commandos in whose midst he was, to be seeking a heroic death in action) was regularly to be seen on the deck blazing away at the oncoming hostile aircraft with a Tommy Gun.

[5] Cowan also saw action subsequently at the Battle of Bir Hakeim, where, having attached himself to the Indian 18th King Edward VII's Own Cavalry, he was captured on 27 May 1942,[1] having fought an Italian tank crew single-handedly armed only with a revolver.

He was repatriated in 1943 under an agreement with Italy whereby some 800 Italian seamen interned in neutral Saudi Arabia from the Red Sea Flotilla were exchanged for a similar number of British prisoners of war.

After the war he was invited to become the honorary colonel of the 18th King Edward's Own Cavalry, and visited India to receive the post, which he considered the greatest he had attained in his extensive military career.