What was Germany doing with their U - boats? How did it influence America?

On this day in 1917, Germany announces the renewal of unrestricted submarine warfare in the Atlantic as German torpedo-armed submarines prepare to attack any and all ships, including civilian passenger carriers, said to be sighted in war-zone waters.

When World War I erupted in 1914, President Woodrow Wilson pledged neutrality for the United States, a position that the vast majority of Americans favored. Britain, however, was one of America's closest trading partners and tension soon arose between the United States and Germany over the latter's attempted blockade of the British isles. Several U. S. ships traveling to Britain were damaged or sunk by German mines and, in February 1915, Germany announced unrestricted warfare against all ships, neutral or otherwise, that entered the war zone around Britain. One month later, Germany announced that a German cruiser had sunk the William P. Frye, a private American merchant vessel that was transporting grain to England when it disappeared. President Wilson was outraged, but the German government apologized, calling the attack an unfortunate mistake.