Answer:
The Americans helped the British Empire, French and Portuguese forces defeat and turn back the powerful final German offensive (Spring Offensive of March to July, 1918), and most importantly, the Americans played a role in the Allied final offensive (Hundred Days Offensive of August to November).
The entry of the United States was the turning point of the war, because it made the eventual defeat of Germany possible. It had been foreseen in 1916 that if the United States went to war, the Allies' military effort against Germany would be upheld by U.S. supplies and by enormous extensions of credit.
Step-by-step explanation: