On May 7, 1915, the German submarine (U-boat) U-20 torpedoed and sank the Lusitania, a swift-moving British cruise liner traveling from New York to Liverpool, England. Of the 1,959 men, women, and children on board, 1,195 perished, including 123 Americans. The sinking of the Lusitania was not the single largest factor contributing to the entrance of the United States into the war two years later, but it certainly solidified the public's opinions towards Germany. President Woodrow Wilson, who guided the U.S. through its isolationist foreign policy, held his position of neutrality for almost two more years. Many, though, consider the sinking a turning point—technologically, ideologically, and strategically—in the history of modern warfare, signaling the end of the "gentlemanly" war practices of the nineteenth century and the beginning of a more ominous and vicious era of total warfare.

Source: U.S. Department of State