What ocean liner was sunk by a German submarine in 1915?

The ocean liner sunk by a German submarine in 1915 was RMS Lusitania.

The British-registered Lusitania was torpedoed by the German submarine U-20 on May 7, 1915, near the Old Head of Kinsale off Ireland. It was traveling from New York to Liverpool when the attack struck in waters Germany had declared a war zone.

The sinking killed 1,197 of the 1,960 people aboard, including 128 Americans. The large loss of civilian life caused outrage in the United States and intensified anti-German opinion, although the United States did not enter World War I until April 1917.

The Lusitania is often confused with Titanic, which sank in 1912 after striking an iceberg, or Britannic, which sank in 1916 after hitting a mine while serving as a hospital ship. Lusitania was a Cunard liner and a major symbol in debates over submarine warfare.