RMS "Lusitania" was a British ocean liner that was sunk on 7 May 1915 by a German U-boat off the southern coast of Ireland, killing 1,198 passengers and crew. The sinking occurred about two years before the United States declaration of war on Germany. Although the "Lusitania" sinking was a major factor in building support for a war, war was eventually declared only after the Imperial German Government resumed the use of unrestricted submarine warfare against American shipping in an attempt to break the Transatlantic supply chain from the US to Britain, as well as after the Zimmermann Telegram. "Lusitania" held the Blue Riband appellation for the fastest Atlantic crossing and was briefly the world's largest passenger ship until the completion of the three months later. The Cunard Line launched her in 1906 at a time of fierce competition for the North Atlantic trade. She was sunk on her 202nd trans-Atlantic crossing.