The Allied powers were a crucial force in the defeat of the Axis powers during World War II. Led by the United States, United Kingdom, and the Soviet Union, this alliance included numerous other countries that joined forces to fight against the common enemy. Each Allied power played a significant role in the war effort, bringing different strengths and strategies to the table.

The United States, under the leadership of President Franklin D. Roosevelt, emerged as a major global superpower during World War II. Despite its initial reluctance to join the war, the United States provided essential support through its vast industrial capacity, supplying war materiel to the Allies. The country also played a key role in liberating Western Europe and combating Japanese forces in the Pacific theater. Notable military campaigns by the United States include the D-Day invasion of Normandy and the Pacific island-hopping campaign.

The United Kingdom, led by Prime Minister Winston Churchill, played an integral part in the Allied powers' fight against Axis aggression. The country stood strong against German air attacks during the Battle of Britain and successfully defended against Axis invasions in North Africa. The British Army, along with Commonwealth forces, contributed significantly to the Allied victory in various theaters of war, such as the Mediterranean and the Far East.

The Soviet Union, under the leadership of Josef Stalin, bore the brunt of the fighting on the Eastern Front. The Red Army fought resiliently against the German forces, turning the tide of the war with significant victories such as the Battle of Stalingrad. The Soviet Union's immense manpower and industrial capacity played a crucial role in overpowering the Axis powers.

Overall, the Allied powers showcased a united front against the Axis powers' aggression, and their combined efforts were instrumental in securing victory in World War II.