Which event was most influential in turning American public opinion?

The sinking of the RMS Lusitania on May 7, 1915, was a turning point in American public opinion about World War I. The ship was a British ocean liner that was torpedoed by a German U-boat off the coast of Ireland, killing nearly 1,200 people, including 128 Americans. The incident outraged Americans and helped to convince them that Germany was a threat to the United States.

Before the sinking of the Lusitania, most Americans were opposed to the United States entering the war. They believed that the war was a European conflict and that the United States should stay out of it. However, the sinking of the Lusitania changed public opinion. Americans were horrified by the German attack on a civilian ship and they began to believe that the United States needed to do more to protect its citizens.

The sinking of the Lusitania was also a major turning point in the war itself. It helped to convince the United States to enter the war on the side of the Allies. The United States declared war on Germany in April 1917, and its entry into the war helped to turn the tide in favor of the Allies.

In addition to its impact on American public opinion, the sinking of the Lusitania also had a significant impact on the history of the United States. It helped to create a more internationalist foreign policy and it led to the United States becoming a major world power.