Which British ocean liner was famously torpedoed and sunk off the coast of Ireland in 1915?

The Lusitania, owned by the Cunard Line, was built to compete for the highly lucrative transatlantic passenger trade. Construction began in 1904, and, the Lusitania was launched on June 7, 1906. By 1907 it was the largest ship in the world, measuring some 787 feet (240 meters) in length and weighing approximately 31,550 tons; it was surpassed the following year by its sister ship, the Mauretania. Although luxurious, the Lusitania was noted more for its speed. On September 7, 1907, the ship made its maiden voyage, sailing from Liverpool, England, to New York City.

In May 1915 the Lusitania was returning from New York to Liverpool with 1,959 passengers and crew on board. The sinkings of merchant ships off the south coast of Ireland and reports of submarine activity there prompted the British Admiralty to warn the Lusitania to avoid the area and to recommend adopting the evasive tactic of zigzagging, changing course every few minutes at irregular intervals to confuse any attempt by U-boats to plot her course for torpedoing. The ship’s captain, William Thomas Turner, chose to ignore these recommendations, and on the afternoon of May 7, the vessel was attacked. Within 20 minutes the Lusitania had sunk, and 1,198 people were drowned, including 128 US citizens.

The loss of the liner and so many of its passengers aroused a wave of indignation in the USA, and it was fully expected that a declaration of war would follow, but the USA government clung to its policy of neutrality.