Answer:
On April 6 1917, America officially joined the ally power in the world war one after upholding it's policy of neutrality for about three years.
Step-by-step explanation:
As the German aggression increased during the world war 1, the American stance of neutrality decreased and they eventually entered the world war one because Germany blamed much of Britain's actions on the United States which facilitated it's revaluation of neutrality policy.