Final answer:
The Lusitania was a British merchant-passenger ship carrying war supplies, which led to its targeting by a German U-boat, resulting in a tragic sinking that influenced American sentiment about World War I.
Step-by-step explanation:
The Lusitania was a British merchant-passenger ship that was sunk by a German U-boat during World War I. Germany targeted the Lusitania because it was transporting war supplies, specifically ammunition bound for the British army, which was considered contraband and a legitimate target under the rules of war at the time.
The ship's sinking resulted in the death of more than twelve hundred civilians, including 128 American citizens, and marked a significant event contributing to the shift in American public opinion regarding the war.