Final answer:
The last country to officially join the Allied Powers during World War II was the United States, following the attack on Pearl Harbor in December 1941. Other countries like Great Britain and France had already been involved since 1939. This entry of the U.S. marked a pivotal change in the dynamics of the war.
Explanation:
Last Country to Join the Allied Powers
The last country to formally join the Allied Powers during World War II was the United States. Although the United States was initially neutral, its stance changed after the Japanese attack on Pearl Harbor on December 7, 1941. Following this event, the U.S. declared war on Japan on December 8, 1941, and subsequently on Germany and Italy on December 11, 1941.
Other major Allies such as Great Britain and France had been engaged in the war since its beginning in 1939. The involvement of the United States significantly shifted the balance of power in favor of the Allies.
Conclusion
In summary, while several nations were part of the Allies from the beginning, the United States was the last significant country to join the fight, marking a crucial turning point in the war.
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