It was the only attack on the American mainland in the entire First World War. The said U-156 was a German submarine of the powerful class Deutschland.
The German submarine U-156 carried out an unusual feat, on July 21, 1918, shelling the American city of Orleans in Massachusetts. It was the only attack on the American mainland in the entire First World War. The said U-156 was a submarine of the powerful class Deutschland. They were the largest submarines in use during the First World War and were originally conceived as cargo submarines for smuggling goods from the US to Germany during the British naval blockade. They were later converted into attack submarines and equipped with 18 torpedoes and two powerful 105-millimeter cannons. It was with these cannons that it attacked the U-156 area around the city of Orleans, near the protruding Cape Cod in the Atlantic Ocean.
Several grenades hit the city and left the craters from the explosions. The damage was not great, but the psychological effect on the population was strong. Namely, the mainland of the USA has not been attacked since 1846. The U-156 submarine under command managed to leave the area undamaged and headed north in further attacks on American and Canadian ships. The U.S. mainland was no longer under attack until World War II, when Japanese submarines attacked the West Coast on two occasions.