SM U-151 or SM Unterseeboot 151 ( ex U Oldenburg) 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 34 ships sunk () and 7 ships damaged (13,267 GRT and 1,025 tons). Background U-151 was originally one of seven 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 SK L/45 deck guns, including U-151 which was originally to have been named Oldenburg. The Type U 151 class 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 U-151 claimed her first victim, the 3,104 GRT French sailing ship Blanche in the Atlantic Ocean. On 2 or 12 October 1917 (sources differ), she collided with the Royal Navy Q-ship in the Atlantic Ocean off Casablanca, French Morocco, sinking Begonia. 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 off the United States East Coast on 21 May, laid mines off the Delaware Capes and cut the submerged telegraph cables which connected New York City with Nova Scotia. On 25 May she stopped three American 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 American ships and damaged one 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. Thirteen people died in the seven sinkings, their deaths caused by a capsized lifeboat from . On 9 June 1918, U-151 stopped the Norwegian cargo ship Vindeggen off Cape Hatteras, North Carolina. Scuttling charges