How Did The United States Become Involved In World War I?

The United States were interested in the Allied victory, and besides saw the war as a great source of profit: J.P. Morgan, for example, helped to fund British and French military campaigns, providing them with loans on more than $3 billion. In 1915, a German submarine sunk "Lusitania" - an American civil ship; it resulted in 128 deaths of the American citizens, serving the United States as a reason to join the war against Germany. Besides, the very fact of submarines being widely used by German forces was a threat to the naval dominance of the United States, which they could not leave unanswered.