How did Germany's use of unrestricted submarine warfare bring America into World War I?

1 Answer
May 22, 2018

Specifically the sinking of the Lusitania and its aftermath.

Explanation:

The Lusitania was torpedoed in 1915 with the loss of over 1,00 lives including 128 Americans. There was an outcry in the US. However President Wilson held off declaring war.
2 years later when the Germans announced unrestricted submarine warfare, this pushed American public opinion over the brink and the USA declared war on Germany.