Harling, a keen amateur sailor, volunteered for the Royal Navy. Before he finished training, under the legendary Captain O. M. Watts, he found himself at Dunkirk in charge of a whaler. Sub-Lieutenant Harling, RNVR, next found himself navigator of a corvette, on convoy duty in the Western Approaches. This led him to write "The Steep Atlantick Stream", published by Chatto &amp; Windus in 1946, based on his experiences in the North Atlantic and Mediterranean between 1941 and 1942.