RMS Lusitania was a British luxury ocean liner owned by the Cunard Steamship Company and built by John Brown and Company of Clydebank, Scotland. Christened and launched on Thursday, 7 June 1906, Lusitania (sister ship of RMS Mauretania), met a disastrous end as a casualty of the First World War when she was torpedoed by the German submarine U-20 on 7 May 1915. The great ship sank in just 18 minutes, eight miles (15 km) off the Old Head of Kinsale, Ireland, 1,198 of the people aboard were killed. The first British four-stacker, Lusitania was also the world's first quadruple screw steamer and the first ship to exceed 30,000 tons

On 4 February 1915 Germany declared the seas around the British Isles a war zone, so from 18 February, Allied ships in the area would be sunk without warning. This was not wholly unrestricted submarine warfare since efforts would be taken to avoid sinking neutral ship
Lusitania wasn't due to arrive in Liverpool until 6 March 1915. The Admiralty issued her specific instructions on how to avoid submarines. Despite a severe shortage of destroyers, Admiral Henry Oliver ordered HMS Louis and Laverock to escort Lusitania, and took the further precaution of sending the Q ship Lyons to patrol Liverpool Bay. Captain Dow of Lusitania, not knowing whether Laverock and Louis were actual Admiralty escorts or a trap by the German navy, evaded the escorts and arrived in Liverpool without incident

Lusitania departed Pier 54 in New York on 1 May 1915. The German Embassy in Washington had issued this warning on 22 April.

This warning was printed right next to an advertisement for Lusitania's return voyage. The warning led to some agitation in the press and naturally worried the ship's passengers and crew.

At about 11:00, on Friday, 7 May, the Admiralty radioed another warning, and Turner adjusted his heading northeast, apparently thinking submarines would be more likely to keep to the open sea, so that Lusitania would be safer close to land. U-20 was low on fuel and only had three torpedoes left, and Schwieger had decided to head for home. She was moving at top speed on the surface at 13:00 when Schwieger spotted a vessel on the horizon. He ordered U-20 to dive and to take battle stations. The previous week, U-20 had encountered a small cargo vessel and allowed the crew to escape in the boats before sinking it; Schweiger could have allowed the crew and passengers of the Lusitania to take to the boats, but due to the Q-ship program, he considered the danger of being rammed or fired upon by deck guns too great. The Lusitania's captain had, in fact, been ordered to ram any U-boat that surfaced; a cash bonus had been offered for successful ramming.

The torpedo struck Lusitania under the bridge, sending a plume of debris, steel plating and water upward and knocking Lifeboat #5 off its davits, and was followed by a much larger secondary explosion in the starboard bow.
Lusitania's wireless operator sent out an immediate SOS and Captain Turner gave the order to abandon ship. Water had flooded the ship's starboard longitudinal compartments, causing a 15-degree list to starboard making the launch of her lifeboats complicated. Lusitania had 48 lifeboats, more than enough for all the crew and passengers, but only six were successfully lowered, all from the starboard side.

Lusitania sank in 18 minutes, 8 miles. 1,198 people died with her, including almost a hundred children. The bodies of many of the victims were buried at either Lusitania's destination, Queenstown, or the Church of St. Multose in Kinsale, but the bodies of the remaining 884 victims were never recovered.

Read about survivor Rev. Herbert Linford Gwyer, Second Cabin Passenger aboard the RMS Lusitania, 1915 here