What was the Most Important War in American History?

Extract

[...] What was the Most Important War in American History? In your opinion, what was the most important war in American history? Why? In my opinion, the Second World War was the most important in American history. However, the Americans only entered the conflict in December 1941 following the Japanese aggression on its ground at Pearl Harbor on the 7th. Roosevelt refused neutrality and isolationist policy defended by the Monroe Doctrine to support his allies. The United States was already providing logistical, financial and material aid, notably to the United Kingdom through the Lend-Lease System, which began in March 1941, while at the same time stopping their oil imports to Japan. [...]

[...] Within a few months, Nazi Germany and Fascist Italy were defeated, showing the power of the American military strike. In the Pacific, it was Harry Truman, Roosevelt's successor, who decided to launch the first two atomic bombs in history on Hiroshima and Nagasaki on 6 and 9 August 1945 to stop Japan, which caused more than 300,000 victims. At the end of the conflict, the United States took part in the "Big Three" in Yalta and Potsdam, the future of Europe was decided with the partition of Germany into several zones of occupation. [...]