On this day in 1917, driven by the spectacular success of the German U-boat submarines and their attacks on Allied and neutral ships at sea, the British Royal Navy introduces a newly created convoy system, whereby all merchant ships crossing the Atlantic Ocean would travel in groups under the protection of the British navy.
For more than three years of World War I, Britain's Royal Admiralty steadfastly resisted the creation of a convoy system, believing they could not afford to spare ships and other resources from its mighty fleet where they might be needed in battle. The effect of the German U-boat submarines, however, and their attacks on merchant ships—both belligerent and neutral—proved devastating. With the entrance of the United States into the war in April 1917, there was an even greater need for protection of Allied interests at sea, as large numbers of soldiers and arms would need to be transported from the Atlantic coast to Europe. In early May 1917, it was announced that the previous month had seen the highest shipping losses of the war so far for Allied and neutral countries: 373 ships, or a total weight of 873,754 tons.
Consequently, on May 24, 1917, Britain introduced its convoy system. Under the new arrangements, a convoy of 10 to 50 merchant ships—along with, possibly, a troopship carrying arms and soldiers—might be escorted by a cruiser, six destroyers, 11 armed trawlers and a pair of torpedo boats with aerial reconnaissance equipment that could detect the movement of underwater submarines. Convoy gathering points were established along the Atlantic coast of North and South America, from Halifax, Nova Scotia, to Hampton, Virginia, all the way down to Rio de Janeiro, Brazil, to handle the transport not only of men and arms but also of foodstuffs and horses, the basic supplies of the Allied war effort.
The introduction of the convoy system finally marked the beginning of a sharp decline in the scale of German submarine damage and the death of German hopes to starve Britain into submission. Between May 1917 and November 1918, a total of 1,100,000 American troops were transported across the Atlantic in convoy, and only 637 of them were drowned as a result of German attacks.