On This Day in History: The Convoy System

Naval History and Heritage Command photograph
Courtesy of Paul Silverstone, 1982

The first transatlantic convoy to reach Great Britain departed Hampton Roads, Virginia, on this day in 1917. The United States had entered World War I the previous month and now faced the challenge of how to get men and material safely to the European theater. Germany’s u-boats had been operating in the North Sea and Atlantic Ocean since the early days of the war and made any voyage a risky proposition. They were so effective that by April 1916, the British were rationing food to civilians and had only a six weeks’ supply of wheat left in reserve.

One reason the u-boats were initially so successful was that for the first three years of the war, merchant ships sailed individually with no warships escorting them. Great Britain’s Admiralty felt that grouping ships together in convoys only presented a larger target to prowling submarines, and that the chances for detection were much less if the ships spread out and made their own way across the ocean. Inevitably, the u-boats would find some of them and sink them, but the Admiralty assumed that this method would minimize losses.

Vice Admiral William Sims, former President of the Naval War College and commander of all U.S. naval forces in Europe, disagreed. In his meetings with First Sea Lord Sir John Jellicoe, he pressed the Royal Navy to adopt the convoy system. April 1917 had seen the highest shipping losses of any month so far during the war: 373 ships from Allied and neutral countries weighing 873,754 tons. By May, Jellicoe was ready to authorize convoys as long as the U.S. promised to provide some of the escorts. The first convoy left Gibraltar on May 10 with seventeen ships and two escorts, arriving safely in Great Britain twelve days later. The second left from Hampton Roads on May 24 escorted by HMS Roxburgh and lost only one ship to u-boat attack.

Naval History and Heritage Command photograph

The Americans borrowed some tricks from their British counterparts to further frustrate the efforts of the u-boat captains. One of these was a unique camouflage scheme known as dazzle. In order to make a successful torpedo attack, u-boats had to observe a target for an extended length of time and correctly estimate its size, range, speed, and heading. Unlike other camouflage schemes, dazzle did nothing to prevent a ship from being detected. Instead, the jarring patterns of lines, curves, and stripes broke up the ship’s outline and made it very difficult for an observer to determine at what angle he was viewing the target.

WWI Victory Loan Drive Poster, 1918

Leon Alaric Shafer (1866-1940)

Library of Congress

It remains difficult to say whether or not dazzle actually worked better than other camouflage schemes. Of the convoy system, however, there can be no doubt that it greatly contributed to the Allied war effort by ensuring the safe passage of thousands of merchantmen and troop ships. Karl Doenitz, the man who would go on to lead Germany’s u-boat campaign during the Second World War, said of the introduction of the convoy system:

The oceans at once became bare and empty. For long periods at a time, the U-boats, operating individually, would see nothing at all; and then suddenly up would loom a huge concourse of ships, thirty or fifty or more of them, surrounded by a strong escort of warships of all types. The solitary U-boat, which most probably had sighted the convoy purely by chance, would then attack, thrusting again and again ... for perhaps several days and nights until the physical exhaustion of the command and crew called a halt. The lone U-boat might well sink one or two ships, or even several, but that was a poor percentage of the whole. The convoy would steam on. In most cases, no other German U-boat would catch sight of it and it would reach Britain, bringing a rich cargo of foodstuffs and raw materials safely to port.

Rob Doane

Curator, Naval War College Museum