Final answer:
The first U.S. action against Axis forces in the European theater was Operation Torch, a combined U.S. and British invasion of North Africa in November 1942.
Step-by-step explanation:
The first U.S. action against Axis forces in the European theater was Operation Torch. Operation Torch was a combined U.S. and British invasion of North Africa in November 1942. The goal was to relieve pressure on the Soviet Union and open up a second front against the Axis forces. The invasion was successful and marked the beginning of the U.S. involvement in the European theater.