What was the United States’ contribution to Germany’s defeat in WWI?

The massive manpower of the United States had overwhelmed German forces.

Explanation:

The Americans had helped push back the Germans after the long stalemate of trench warfare. They had used weapons such as the shotgun to cause massive casualties to German troops. As they pushed back to German borders, Germany had agreed to an armistice, officially ending the war.

norsemen from northern countries had made earlier journeys

rosevelt. 1973. "slaves everywhere"