With the bombing at Pearl Harbor on December 7, 1941, the United States was pulled into another conflict we hoped to avoid.  American entry into WWII was vital to the success of the Allies and the horrors of war were fully realized when we stumbled upon the Nazi concentration camps and understood Hitler's vision for post-war Europe.  The United States will also unleash the use of the Atomic Bomb on Japan to end WWII, which directly contributes to the Cold War era that America was plagued by for the next 50 years, and still impacts us today.