The sinking caused diplomatic tensions between Germany and the neutral United States. The attack came without prior warning, resulting in the deaths of 1,198 people, including over 100 American civilians. This incident intensified support for the Allied Powers among the American public and was one of the factors that led to the United States' eventual entry into World War I on the side of the Allies in April 1917.
Following the sinking, the United States government sent a series of diplomatic notes to Germany, including the Lusitania Note, condemning the act and demanding compensation and assurances that such attacks would not occur again. Germany refused to change its unrestricted submarine warfare policy, arguing that it was necessary due to the Allies' blockade.
The Lusitania's sinking sparked intense public outrage in the United States and fueled anti-German sentiment. It was seen as a deliberate act of violence against non-combatants and civilians. The incident had a profound impact on the course of World War I and contributed to the shift in public opinion in the United States towards supporting the Allies.
Although the Lusitania's sinking was not the sole reason for the United States' entry into World War I, it was a significant event that contributed to the tensions and grievances between the United States and Germany. It served as a catalyst for the growing animosity and mistrust, eventually leading to the United States' involvement in the conflict.