Cross-Section of a Submarine (1915)
At first, Admiral Alfred von Tirpitz (1849-1930) failed to regard submarines as an important factor in naval warfare. Several advances – including the installation of diesel engines, the refinement of the naval periscope, and the construction of self-propelled torpedoes – contributed to the increasing importance of submarines in the period leading up the First World War. Initially, submarines were reserved for exclusive use in reconnaissance missions. Later, they were also deployed to sink enemy merchant and naval vessels in order to cut Britain off from supplies. On May 7, 1915, a German submarine sank the passenger ship Lusitania. German authorities rightly suspected that the ship was transporting contraband weapons. The incident claimed more than a thousand lives, with more than 100 American citizens numbering among the dead. As a result, the U.S. launched vehement protests, prompting the German government to cease unannounced attacks on neutral merchant ships. With the escalation of the war effort in early 1917, however, the German High Command succeeded in winning Reichstag approval for the recommencement of unrestricted submarine warfare. The consequences were enormous, as German submarines sank about 7 million gross tons (GRT) of Entente and neutral shipping that year. But contrary to expectations, the attacks did not force Britain to its knees. Moreover, they caused the United States to declare war on Germany on April 6, 1917.
This drawing shows the cross-section of one of the 380 German submarines deployed in World War I. In September of 1914, the U21 submarine (the model depicted here) became the first submarine to sink an enemy naval vessel with a self-propelled torpedo; in 1915, it played a crucial role in the failed Allied attempts to capture Gallipoli and occupy the Dardanelles. Issued in 1915, this picture postcard by W.B. Lewy was part of a wartime propaganda campaign to popularize the various branches of the German armed service.