U.S. Entry into World War II
The Japanese attack on Pearl Harbor on December 7, 1941, marked the United States' full entry into World War II. This event answered the question of "Why did America join WW2?" and set in motion a massive mobilization effort.
Key immediate actions by the U.S. government included:
- Declaring war on Japan and the other Axis powers
- Mobilizing the economy and military for total war
- Implementing measures to identify potential security threats
Definition: Total war - A conflict in which countries mobilize all available resources, including civilian population and industry, towards the war effort.
The U.S. adopted a "Germany First" strategy, prioritizing the defeat of Nazi Germany while also fighting Japan in the Pacific. This decision was based on the assessment that Germany posed a greater immediate threat to global security.
Highlight: The "shoot on sight" policy authorized U.S. naval forces to engage German submarines in the Atlantic even before the formal declaration of war.
The war effort also had significant domestic impacts, including:
- Executive Order 9066, leading to the internment of Japanese Americans
- Limitations on civil liberties in the name of national security
- Creation of the War Refugee Board to assist victims of Nazi persecution
These actions reflect the complex balance between national security concerns and civil liberties during wartime.











