The Allies (USA, Canada, Britain, Soviet Union etc.) agreed to pool their resources and fight the Axis powers as a joint operation. Because of the greater industrial output of the USA and the increased manpower, the Allies were able to make inroads towards defeating the enemy which hadn't been possible before.
The 8th of December 1941 was the date that the US joined world war 2
Pearl Harbour.
They joined in1941
1941 .
joined in 1942
8 December 1941
we were on the allied we joined after the attack on pearl harbor
The United States of America joined the Allied Nations in World War II.
nato
United Nations
The U.S.A. officially joined World War 2 when the Japanese attacked Pearl Harbor in 1945.
When the US joined the war in 1941, they joined with the Allied Powers. Italy was a part of the Axis powers. They had to fight each other.