A convoy is when a number of merchant vessels or troop ships sail close together with a naval escort for protection. This was not a new idea and had been widely used in the Age of Sail. However it was revived in the First World War in response to a specific threat – the development of the submarine.
German submarines - known as U-boats – would travel in groups below the sea, approach the surface to torpedo an unsuspecting ship, then disappear into the depths. Allied losses to U-boats were high. The new technology and tactics demanded a response. There was disagreement about what that response should be. The Admiralty was not keen to use its limited resources protecting merchant ships, arguing that the ships of the Royal Navy would be better employed in offensive rather than defensive duties.
Gradually however, the convoy system was adopted largely due to political will. The earliest convoys in the First World War had been to provide escorts for troop ships but the first regular British convoy was from the Hook of Holland to Harwich, which ran from July 1916 with 1,861 sailings and only 7 losses before the end of the war. This route was vital because it brought so much food to Britain. Indeed it was nicknamed ‘The Beef Trip’. The escorts were destroyers from the Harwich Force and, later on, AD Flying Boats based in Felixstowe, demonstrating how valuable aircraft were as escorts around coastal waters. Coal convoys were established in February 1917 to protect coal ships crossing the Channel and these also benefitted from the protection of escorting aircraft. Only 53 coal ships were lost in 39,352 sailings. Convoys were not confined to short journeys; ocean convoys escorted vessels across the Atlantic where losses in convoys dropped to ten percent of those suffered by independent ships.
The statistics spoke for themselves and the convoy system was not the only defence. Technologies were developed to combat the submarine threat. Depth charges exploded underwater to destroy submarines and hydrophone made it possible to detect submarines by listening for them underwater. The demonstrable success of the convoy system meant that it continued to be used in the Second World War.
Researched and written by Forgotten Wrecks volunteer Pauline Blagden