The continued attacks at the ships and killing of American citizens by Germany led to US entering the World War.
Explanation:
At the start of the First World War, the United States was a neutral nation and would have likely remained one had it not been for the continued attacks by Germany. At this point in time, America was just a trading partner of Britain and did not really get involved in any of the ongoing war between the Allied Powers of which Britain was a member and the Central powers of which Germany was a part.
But the attack and continued warfare on the ships sailing to America by Germany led to the entry of the United States into the war. First was the sinking of several ocean liners, including <em>Lusitania</em>, and <em>William P. Frye (a private vessel)</em>, which the Germans believed carried weapons. The British/ Americans maintained these ships were just passenger ships with American citizens. Germany did not stop the attacks on vessels and ships, continuously killing American citizens and continued the sea warfare, thereby pushing President Woodrow Wilson to declare the US's decision to side with the Allied Powers in the war.
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