This map is part of a series of 20 animated maps showing the history of The first World War, 1914-1918.
On 22 September, 1914, a German submarine sank 3 British battleships. The display of this new weapon’s effectiveness spurred Berlin to increase its production of submarines and to favour their use against the Allies’ merchant ships.
In January 1917, Germany decided to intensify its submarine warfare with the goal of destroying 600,000 tons of shipping per month in order to bring England to its knees and force it to capitulate. This submarine campaign rapidly led to considerable losses, but at the same time drew the United States into the conflict.
The Allies gradually improved their defences against German submarines and regrouped their merchant ships into convoys on the main maritime routes, which facilitated their protection.
For all this, destruction of merchant ships did not stop, but the attempt to choke England failed.