At the time of her sinking, the LUSITANIA was the world's largest passenger liner. She was owned by the British-American Cunard Line. Although unarmed and therefore defenceless, it is probable that the Germans believed that she was carrying munitions and this provoked the U-boat attack on 7 May 1915. Source: Detroit Publishing Co., Copyright Claimant, and Publisher Detroit Publishing Co. The Lusitania. Photograph. Retrieved from the Library of Congress.