WHY DID THE USA ENTER THE WAR IN 1915?From the start of the Great War, the name by which World War I was first known, British
warships blockaded German ports. In this way Britain’s navy prevented
supplies from reaching Germany, causing severe shortages of food and other goods. The Germans retaliated with their submarines, called U-boats. After 1915, U-boats attacked both warships and merchant shipping
carrying supplies to Britain. In May 1915, a German torpedo hit a British passenger ship called the Lusitania. The ship was carrying nearly 2,000 passengers, including many Americans. The sinking of the Lusitania was one of the factors that eventually drew the United stats into the war