Otto Weddigen sank the obsolete British warships , , and (the "Live Bait Squadron") in a single hour. In the Gallipoli Campaign in early 1915 in the eastern Mediterranean, German U-boats, notably the U-21, prevented close support of allied troops by 18 pre-dreadnought battleships by sinking two of them. For the first few months of the war, U-boat anticommerce actions observed the "prize rules" of the time, which governed the treatment of enemy civilian ships and their occupants. On 20 October 1914, sank the first merchant ship, , off Norway. Surface commerce raiders were proving to be ineffective, and on 4 February 1915, the Kaiser assented to the declaration of a war zone in the waters around the British Isles. This was cited as a retaliation for British minefields and shipping blockades. Under the instructions given to U-boat captains, they could sink merchant ships, even potentially neutral ones, without warning. In February 1915, a submarine U-6 (Lepsius) was rammed and both periscopes were destroyed off Beachy Head by the collier SS Thordis commanded by Captain John Bell after firing a torpedo. On 7 May 1915, sank the liner RMS Lusitania. The sinking claimed 1,198 lives, 123 of them American civilians, and the attack of this unarmed civilian ship deeply shocked the Allies. According to the ship's manifest, Lusitania was carrying military cargo, though none of this information was relayed to the citizens of Britain and the United States, who thought that the ship contained no ammunition or military weaponry whatsoever and it was an act of brutal murder. Munitions that she carried were thousands of crates full of ammunition for rifles, 3-inch (76 mm) artillery shells, and various other standard ammunition used by infantry. The sinking of the Lusitania was widely used as propaganda against the German Empire and caused greater support for the war effort. A widespread reaction in the U.S was not seen until the attack on the ferry , which carried many citizens of the United States. The initial U.S. response was to threaten to sever diplomatic ties, which persuaded the Germans to issue the Sussex pledge that reimposed restrictions on U-boat activity. The U.S. reiterated its objections to German submarine warfare whenever U.S. civilians died as a result of German attacks, which prompted the Germans to fully reapply prize rules. This, however, removed the effectiveness of the U-boat fleet, and the Germans consequently sought a decisive