In February, 1915, the German government announced an unrestricted warfare campaign. This meant that any ship taking goods to Allied countries was in danger of being attacked. This broke international agreements that stated commanders who suspected that a non-military vessel was carrying war materials, had to stop and search it, rather than do anything that would endanger the lives of the occupants.
The Lusitania, was at 32,000 tons, the largest passenger vessel on transatlantic service, left New York harbour for Liverpool on 1st May, 1915. It was 750ft long, weighed 32,500 tons and was capable of 26 knots. On this journey the ship carried 1,257 passengers and 650 crew.
There was some concern on board as a few days previously the German Embassy had published a statement that warned: "Travellers intending to embark for an Atlantic voyage are reminded that a state of war exists between Germany and her allies and Great Britain and her allies; that the zone of war includes the waters adjacent to the British Isles; that in accordance with the formal notice given by the Imperial German Government, vessels flying the flag of Great Britain or any of her allies are liable to destruction in those waters; and that travellers sailing in the war zone in ships of Great Britain or her allies do so at their own risk."
At 1.20pm on 7th May 1915, the U-20, only ten miles from the coast of Ireland, surfaced to recharge her batteries. Soon afterwards Captain Schwieger, the commander of the German U-Boat, observed the Lusitania in the distance. Schwieger gave the order to advance on the liner. The U20 had been at sea for seven days and had already sunk two liners and only had two torpedoes left. He fired the first one from a distance of 700 metres. Watching through his periscope it soon became clear that the Lusitania was going down and so he decided against using his second torpedo.
After a second, larger explosion, the Lusitania rolled over and sank in eighteen minutes. The Manchester Guardian reported on 10th May, 1915: "The death roll in the Lusitania disaster is still not certainly known. About 750 persons were rescued, but of these some 50 have died since they were landed. Over 2,150 men, women and children were on the liner when she left New York, and since the living do not number more than 710, the dead cannot be fewer than 1,450. What the American people think of the crime is plain. Their newspapers are violent in denunciation; the public, except for the German-Americans, who have celebrated the event as a great and typical victory for their native country, are enraged. How President Wilson regards the affair no one knows. A semi-official statement issued from the White House says he knows the nation expects him to act with deliberation as well as firmness."
A total of 1,198 people died (785 passengers and 413 crew). Those killed included 128 US citizens. The sinking of the Lusitania had a profound impact on public opinion in the United States. The German government apologized for the incident, but claimed its U-boat only fired one torpedo and the second explosion was a result of a secret cargo of heavy munitions on the ship. If this true, Britain was guilty of breaking the rules of warfare by using a civilian ship to carry ammunition. British authorities rejected this charge and claimed that the second explosion was caused by coal dust igniting in the ship's almost empty bunkers.
Howard Zinn, the author of A People's History of the United States (1980), has argued: "It was unrealistic to expect that the Germans should treat the United States as neutral in the war when the U.S. had been shipping great amounts of war materials to Germany's enemies... The United States claimed the Lusitania carried an innocent cargo, and therefore the torpedoing was a monstrous German atrocity. Actually, the Lusitania was heavily armed: it carried 1,248 cases of 3-inch shells, 4,927 boxes of cartridges (1,000 rounds in each box), and 2,000 more cases of small-arms ammunition. Her manifests were falsified to hide this fact, and the British and American governments lied about the cargo."
In 1982 it was announced that attempts would be made to salvage The Lusitania: This created panic in Whitehall. Noel Marshall, the head of the Foreign Office's North America department, admitted on 30th July 1982: "Successive British governments have always maintained that there was no munitions on board the Lusitania (and that the Germans were therefore in the wrong to claim to the contrary as an excuse for sinking the ship). The facts are that there is a large amount of ammunition in the wreck, some of which is highly dangerous. The Treasury have decided that they must inform the salvage company of this fact in the interests of the safety of all concerned. Although there have been rumours in the press that the previous denial of the presence of munitions was untrue, this would be the first acknowledgement of the facts by HMG."