SM U-151

SM U-151 or SM Unterseeboot 151 was a World War I U-boat of the Imperial German Navy, constructed by Reiherstieg Schiffswerfte & Maschinenfabrik at Hamburg and launched on 4 April 1917. From 1917 until the Armistice in November 1918 she was part of the U-Kreuzer Flotilla, and was responsible for sinking 37 ships.

Background
The U-151 was originally one of seven Deutschland class U-boats designed to carry cargo between the United States and Germany in 1916. Five of the submarine freighters were converted into long-range cruiser U-boats (U-kreuzers) equipped with two 105mm deck guns, including the U-151 which was originally to have been named Oldenburg. They were the largest U-boats of World War I.

Service history
U-151 was commissioned on 21 July 1917. From 21 July to 26 December 1917 she was commanded by Waldemar Kophamel who took U-151 on a long-range cruise which eventually covered a total of 12,000 miles. On 19 September 1917 the U-151 claimed her first victim, the 3,104 ton French sailing vessel Blanche in the Atlantic. On 20 November 1917 U-151 captured the steamship Johan Mjelde, and scuttled her on 26 November after transferring 22 tons of her cargo of copper.

American cruise
U-151 left Kiel on 14 April 1918 commanded by Korvettenkapitän Heinrich von Nostitz und Jänckendorff, her mission to attack American shipping. She arrived in Chesapeake Bay on 21 May where she laid mines off the Delaware capes, and cut the submerged telegraph cables which connected New York with Nova Scotia. On 25 May she stopped three US schooners off Virginia, took their crews prisoner, and sank the three ships by gunfire.

On 2 June 1918, known to some historians as "Black Sunday", U-151 sank six US ships and damaged two others off the coast of New Jersey in the space of a few hours. The next day the tanker Herbert L. Pratt struck a mine previously laid by U-151 in the area but was later salvaged. 13 people died in the seven sinkings, their deaths caused by a capsized lifeboat from SS Carolina.

On 9 June U-151 stopped the Norwegian freighter Vindeggan off Cape Hatteras. Scuttling charges were rigged aboard her then she was escorted outside the sea lane under a prize crew. Von Noztitz then transferred 70 tons of copper ingots from the Vindeggan to the U-151.

On the 18th of June, U-151 sank the SS Dwinsk, and then loitered near her lifeboats in the hopes that more Allied shipping would be attracted to them. Through this ruse, she launched torpedoes at the USS Von Steuben (ID-3017), but missed and was instead depth charged by the Von Steuben.

U-151 returned to Kiel on 20 July 1918 after a 94-day cruise in which she had covered a distance of 10915 mi. Her commander reported that she had sunk 23 ships totalling 61,000 tons and had laid mines responsible for the sinking of another 4 vessels.

Fate
At the end of the war U-151 was surrendered to France at Cherbourg, where she was turned into a target ship, and was sunk on 7 June 1921.