SM UB-6 - Second Submarine Offensive

Second Submarine Offensive

By early 1916, the British blockade of Germany was beginning to have an effect on Germany and her imports. The Royal Navy had stopped and seized more cargo destined for Germany than the quantity of cargo sunk by German U-boats in the first submarine offensive. As a result, the German Imperial Navy began a second offensive against merchant shipping on 29 February. The final ground rules agreed upon by the German Admiralstab were that all enemy vessels in Germany's self-proclaimed war zone would be destroyed without warning, that enemy vessels outside of the war zone would be destroyed only if armed, and—to avoid antagonizing the United States—that enemy passenger steamers were not to be attacked, regardless of whether in the war zone or not.

UB-6's first attack in the new offensive came on 17 March, when the U-boat torpedoed the Swedish ship Ask near the North Hinder lightship. The 1,041-ton ship was en route to London from Westervik with a load of timber, but did not sink; there were no reports of casualties on the damaged ship. The attack on Ask was followed up two weeks later by the sinking of another Swedish ship. The 1,115-ton Hollandia was at anchor 0.25 nautical miles (460 m) from the Galloper lightship when UB-4 torpedoed her on the last day of March. Hollandia was in ballast and in the process of sailing from Rouen to Rotterdam when sent under without loss of life.

In March, UB-6's commander, Voigt, was assigned to the newly commissioned UB-23, and replaced on UB-6 by Kapitänleutnant Karl Neumann, the former commander of two of the submarine's sister ships, UB-2 and UB-13. In his U-boat career, Neumann sank over 100,000 tons of shipping, but none at the helm of UB-6. In July, Neumann was succeeded by Oberleutnant zur See Karsten von Heydebreck, a 26-year-old, first-time U-boat captain, who was Voigt's classmate in April 1908 cadet class.

Near the end of April 1916, Admiral Reinhardt Scheer, the newest commander-in-chief of the German High Seas Fleet, called off the merchant shipping offensive and ordered all boats at sea to return, and all boats in port to remain there. As with the end of the first offensive in August 1915, UB-6 would not sink any more ships for the next five months.