German Imperial Navy map showing a dot for each ship sunk by German U-Boats during WW1. Map legend is in German and shows the borders of Europe as they were during the First World War.
The German U-boat campaign began in 1914 and focused on reducing the Royal Navy’s numerical superiority. In response to the British blockade of Germany, the German Navy would begin an unrestricted U-Boat campaign to sink all merchant vessels headed to Britain. In 1917, the German Navy began sinking over 600,000 tons of shipping a month, bringing the British wheat supply to a dangerous low of six weeks worth. In consequence of the German campaign, the USA declared war in April 1917.