SM U-20

The SM U-20 was a German U-19 Type submarine built for the Kaiserliche Marine.  She was commissioned on 5 August 1913.  During World War I she sank 37 ships for a total of 145,830 tons and damaged 2 ships for a total of 2,643 tons.  The largest and most famous ship sank by U-20 was the Cunard passenger ship RMS Lusitania in May 1915, that sinking being one of the major events leading up to America’s participation in the war in 1917.  Later in the war, on 4 November 1916, U-20 ran aground at Vrist, near Thorsminde, on the Danish coast.  Her crew detonated her bow torpedoes to destroy her the next day.

Specifications and history

U-20 was a U-19 Type submarine (the U-19 types being U-19, U-20, U-21, and U-22), ordered on 25 November 1910.  She was built by Kaiserliche Werft in Danzig (now Gdansk, Poland), where her keel was laid on 7 November 1911.  She was launched on 18 December 1912 and commissioned on 5 August 1913.  She was part of the III Flotille of the Kaiserliche Marine.   Her armaments included four 50 cm (19.7 inch) torpedo tubes, two in the bow and two in the stern, that could carry a total of 9 torpedoes.  Additionally, U-20 was equipped with a 1 x 88 mm (3.46 inch) deck gun.  In 1916, she would be refitted to have an additional deck gun. U-20 had two commanders through her career.  The first was Otto Dröscher, who was her commander from 1 August 1914 to 15 December 1914.  Her second commander was Walther Schwieger, who was her commander from 16 December 1914 until the submarine was beached and destroyed on 5 Nov 1916.  Throughout her career she had 7 operations, the most infamous being the one where she sank Lusitania.

The fateful voyage

Under the command of Kapitanleutnant Walther Schwieger, the submarine departed Emden, Germany on 30 April 1915 heading northwest across the North Sea, reaching Peterhead, Scotland on 2 May.  From there, U-20 proceeded around the north of Scotland and Ireland and along the western and southern coast of Ireland.  The plan would be to enter the Irish Sea through the St. George’s Channel to target ships going in and out of Liverpool.  During this time, British Naval Intelligence in Room 40 of the Admiralty was tracking submarine activity, but the information that Room 40 received was not always accurate and not always properly relayed due to micromanagement and excessive secrecy. On 5 May, U-20 sank a merchant schooner, the Earl of LathomU-20 also fired a torpedo at the British steamer Cayo Romano, which was flying a neutral flag, but missed.  At 10:30 that night, the Admiralty sent out a general warning simply stating, “Submarines active off the south coast of Ireland.”  At midnight a clarification “submarine off Fastnet” was added. On 6 May, off the south coast of County Wexford, Ireland, and near the Coningbeg Lightship, U-20 sank the SS Candidate in the morning.  The submarine also sighted to the White Star Liner Arabic but was not able to attack because the ship was too fast, despite sailing a straight course.  That afternoon U-20 sighted and attacked the British SS Centurion, which had not been flying a flag and had her name painted out.  In both instances Schwieger provided ample time for the crews of the attacked ships to evacuate before sinking the ships.  Furthermore, the ships, as small as they were, took a long time to sink despite the submarine torpedoing and firing on the ships. Even though the survivors of these sinkings were rescued, news of the attacks on their ships did not reach Vice-Admiral Coke at Queenstown, who could have relayed this information to LusitaniaLusitania did not receive any specific warnings related to the U-20 sinking these ships as the large ocean liner entered the war zone. On the morning of 7 May, visibility was poor. U-20 was low on fuel and only had three torpedoes left.  Schwieger decided not to take the submarine into the Irish Sea through the St. George’s Channel and decided to begin their way home. Schwieger ordered the submarine to submerge at 11:00 a.m. after sighting a fishing boat that he believed might be a British patrol boat.  Shortly after, the cruiser Juno passed the submerged submarine at high speeds while zigzagging, leaving Schwieger once again being unable to target a ship.  Juno had received warning of submarine activity off Queenstown at 7:45 a.m.

Sinking the Lusitania

U-20’s chief engine room artificer, Friedrich Sellmer, sighted Lusitania at 1:20 p.m. Greenwich Time (2:20 p.m. German time).  Schwieger ordered the submarine to submerge five minutes later to a depth of 11 meters. Observing Lusitania through the periscope, Schwieger did not think that his submarine and Lusitania would be in a line suitable for attack.  Then, Lusitania turned.  Seeing the opportunity, Schwieger brought U-20 into position.  At 700 meter range, Schwieger ordered one gyroscopic torpedo to be fired, running at a depth of 3 meters. According to an unsubstantiated story, Quartermaster Charles Voegele, an Alsatian, refused to carry out the order to fire on a passenger ship and was subsequently court-martialed.  Oberleutnant Raimund Weisbach carried out Schwieger’s order and fired the torpedo at Lusitania. Schwieger's log states that U-20 only fired one torpedo at Lusitania.  While the German Government may have had incentive to alter this log after the international fallout from the sinking, the other crew members of the submarine, in addition to radio reports sent from the submarine to Germany, confirm that only one torpedo was fired. Schwieger had observed the torpedo hit Lusitania and the second, internal explosion that followed.  The second explosion had been so powerful that it even rocked the submarine.  The official log notes the possibility that Lusitania had suffered a boiler or coal explosion, although the account by Weisbach states that the submarine crew had concluded that illegal munitions had caused the explosion. Through the periscope, Schwieger could see the unfolding chaos aboard Lusitania.  The official log states that Schwieger was so disturbed by the sinking that he could not “fire a second torpedo into this crushing crowd of humanity trying to save their lives.” Schwieger gave the periscope to anyone else who wanted to look.  Those who did look recalled at the horrible scene unfolding in front of their eyes, and how they had caused it and were unable to render any assistance.  Later German accounts would say that only then did the submarine’s pilot, Lanz, identify the ship as Lusitania, although this is unlikely, as documents from earlier in the war had identified Lusitania as a prime target. According to the official story, by 2:25 p.m. Schwieger and his men had seen enough.  They dropped the periscope and headed out to sea.  Some Lusitania survivors’ accounts, however, state that they saw a submarine surface, fly a German flag, and walk along the deck of the submarine.  These claims have never been corroborated by any German accounts.


U-20 maintained radio silence on the attack until she was almost back to Germany.  The sinking of the Lusitania was initially received as a great triumph in Germany, although some voices within the country in Vorwärts and the Berliner Tageblatt, criticized the brutality of the action.  By the time U-20 reached Wilhelmshaven, the United States had formally protested to Berlin against the sinking, and Germany attempted to do damage control to save her international reputation. The Lusitania sinking was no longer on occasion to be celebrated, but one of great concern for fear of drawing the United States into the war.  Even though Kaiser Wilhelm II did not agree with the statements within the American note of protest, in order to keep the United States out of the war, Kaiser Wilhelm suspended unrestricted submarine warfare. On 4 September 1915, U-20, under the command of Walther Schwieger, sank the passenger liner, the RMS Hesperian, off of Fastnet, Ireland.  Coincidentally, the Hesperian was carrying the body of Lusitania victim and saloon passenger Frances Stephens, making her twice a victim of the U-20.  Schwieger was ordered to Berlin and required to apologize for going against orders not to sink passenger ships.

End of the U-20

On 4 November 1916, U-20 grounded on the Danish coast at Vrist, near Thorsminde. The U-20 became a curiosity item on the beach and locals traveled to see the stranded submarine.  The submarine crew detonated her bow torpedoes to destroy her the next day.  Schwieger and his crew had even shouted at the gawkers to stay clear as they blew up the submarine, but many stayed to watch as metal flew into the air.  No one was hurt.  The submarine wreck remained a popular local attraction for years. The Danish navy removed the deck gun and cut holes in it to render it unusable. The gun was kept in the naval stores at Holmen in Copenhagen for almost 80 years. The deck gun and conning tower of the submarine are now on display at the Strandingsmuseum, in Thorsminde, West Jutland, Denmark. References: Molony, Senan.  Lusitania:  An Irish Tragedy.  Mercier Press, 2002. Preston, Diana.  Lusitania:  An Epic Tragedy.  Berkley Books, 2002. “RMS Lusitania.” Wikipedia: The Free Encyclopedia. Wikimedia Foundation, Inc. 22 July 2004. Web. 28 April 2011. <> “U-20.” Wikipedia: The Free Encyclopedia. Wikimedia Foundation, Inc. 22 July 2004. Web. 28 April 2011. <> "WWI U-boats: U-20."  Web.  28 April 2011.  <>. “WWI U-boat Successes:  Ships hit by U-20.”  Web.  28 April 2011.  <>.

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