Key Facts
- Ships sunk by U-boats
- ~5,000
- Gross tonnage sunk
- over 12 million gross register tons
- U-boats lost
- 178
- German submariners killed
- ~5,000
- Duration
- 4 years (1914–1918)
Strategic Narrative Overview
German U-boats conducted successive campaigns against Allied and neutral shipping, escalating from restricted to unrestricted submarine warfare. The sinking of passenger liners, including the Lusitania in 1915, caused international outrage and diplomatic pressure. Germany temporarily curtailed attacks before resuming unrestricted submarine warfare in February 1917, a decision that contributed to the United States entering the war. The Allies countered with convoys, depth charges, and improved detection methods, gradually limiting U-boat effectiveness.
01 / The Origins
Both Germany and Britain depended heavily on imports of food, fertilizer, and raw materials to sustain their populations and war industries. Britain's Royal Navy dominated the surface seas, imposing a blockade on Germany, while the Imperial German Navy's surface fleet was largely confined to the German Bight. Faced with British naval superiority, Germany turned to submarine warfare as its primary means of disrupting Allied trade routes around the British Isles and in the Mediterranean.
03 / The Outcome
Despite sinking nearly 5,000 ships totaling over 12 million gross register tons, the U-boat campaign failed to starve Britain into submission. Allied shipbuilding and the convoy system kept available tonnage relatively stable. Germany lost 178 submarines and approximately 5,000 men in combat. The campaign ended with Germany's armistice in November 1918, having caused immense disruption without achieving its strategic objective of forcing Britain out of the war.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Side B
1 belligerent