Sinking of the Lusitania in World War I

In the years leading up to American involvement in World War I, various factors contributed to the nation's eventual decision to join the conflict. One such factor was the increasing hostility between Germany and the United States. As the war progressed, German actions on the high seas, particularly the use of unrestricted submarine warfare, created significant tensions. This provocative strategy not only threatened American lives but also challenged American neutral rights at sea.

One specific incident that heightened these tensions was the sinking of a British ocean liner in 1915. What was the name of this ship, which became a symbol of the dangers of unrestricted submarine warfare?