U-20's torpedo strikes the Lusitania.

As the Lusitania enters the most dangerous part of the voyage, Turner chooses to deviate from the standard practices for evading U-boats. Instead of zig-zagging in at high speed, Turner sails a relatively straight path and slows the Lusitania down to cope with the patchy fog. At 11:00 a.m., after receiving another radio warning from the Admiralty, Turner adjusts the ships’ course to the northwest, apparently reasoning that U-boats would be more likely to stay in the open sea and that the Lusitania would be safer close to the coast. It will prove to be a deadly mistake.

Meanwhile, the U-20 is running low on fuel and has just three of its seven torpedoes left. Captain Schwieger decides to return to Germany. But at 1:00 p.m, as the U-boat is moving along the surface at its top speed of 13 knots, Schwieger spots the liner on the horizon. He orders the crew to take the U-20 underwater and to take up battle stations. Though the liner would have been fast enough to outrun the submerged U-20, the unsuspecting Turner orders the his ship to turn 30 degrees, a course change that will bring the liner across the U-boat’s bow, making it easier to attack. At 2:10 p.m., just 14 miles from the Irish coast, the U-20 and the Lusitania cross paths. Schwieger gives the order to fire. A single torpedo from the U-20 strikes the Lusitania on the starboard side, beneath the bridge, tearing a hole in the ship’s side. A massive secondary explosion blows out the starboard bow.

The Lusitania’s wireless operator sends out an immediate distress call, and Turner gives the order to abandon ship. But the severe list to starboard makes it difficult to lower the lifeboats. Ultimately, only six of the 48 lifeboats manage to reach the water and stay afloat. Schwieger observes the carnage though his periscope before leaving the scene at 2:25 p.m. Three minutes later, the Lusitania, turned on its side with its stem pitched in the air, sinks beneath the waves. In Queenstown, Vice Admiral Charles Coke, who has received the Lusitania’s SOS, dispatches all the available ships to the rescue. They arrive on the scene just before 4:30 p.m. and pick up the Lusitania’s 746 survivors.