The 1920s saw significant cultural changes in America. President Roosevelt declared neutrality for the US in the early years of WWII while Churchill watched without acting in Britain. After France fell to Germany, Roosevelt and Churchill formed an alliance to save Britain. WWII ended the Great Depression globally and established the US as a global police force while devastating Europe's Western empires. Japan emerged as a superpower but attacked Pearl Harbor due to anti-American sentiments, causing widespread US racism against Japanese people with lingering effects.