What events led to the US entering WWII?

The US entered WWII following the Japanese attack on Pearl Harbor and Germany's subsequent declaration of war on the US.

The United States' entry into World War II was precipitated by a series of events that unfolded over a period of time. The most immediate cause was the Japanese attack on the US naval base at Pearl Harbor, Hawaii, on 7th December 1941. This surprise attack resulted in significant loss of life and damage to the US Pacific Fleet, and it shocked the American public, turning the tide of public opinion in favour of entering the war.

However, the path to war had been set much earlier. Throughout the 1930s, as tensions escalated in Europe and Asia, the US maintained a policy of isolationism, preferring to focus on domestic issues rather than become entangled in foreign conflicts. This policy was reflected in a series of Neutrality Acts passed by Congress, which aimed to prevent the US from being drawn into war as it had been during World War I.

Despite this, President Franklin D. Roosevelt was increasingly concerned about the aggressive actions of Germany, Italy, and Japan. He began to prepare the nation for the possibility of war, implementing a peacetime draft and increasing military spending. The Lend-Lease Act of 1941 further signalled a shift away from neutrality, as it allowed the US to provide military aid to countries at war with Germany or Italy.

The final straw came when Germany and Italy, allies of Japan, declared war on the US on 11th December 1941, just days after the attack on Pearl Harbor. This left the US with no choice but to respond in kind, officially entering World War II. The events leading up to the US's entry into the war were a complex interplay of international aggression, domestic policy, and ultimately, direct attack.