How did World War 1 affect US policy?

Isolationism: Prior to World War I, the United States had generally pursued a policy of isolationism, avoiding entanglements in European affairs. However, the war's impact on American society and the economy, as well as the sinking of the Lusitania and other incidents involving American lives and interests, led to a shift in public opinion and a greater willingness to intervene.

Entry into the War: In 1917, the United States declared war on Germany, joining the Allied powers. This decision was influenced by a number of factors, including the resumption of unrestricted submarine warfare by Germany, which threatened American shipping and lives, as well as the revelation of the Zimmermann Telegram, a German diplomatic proposal attempting to secure an alliance with Mexico against the United States.

Mobilization and Economic Impact: The United States mobilized its economy and society to support the war effort. This involved raising a large army and navy, ramping up production of war materials, and implementing various measures of economic control. The war had a significant impact on the US economy, boosting certain industries while disrupting others and leading to inflation and shortages.

Influence on US Foreign Policy: The experience of World War I shaped US foreign policy in the aftermath of the war. It reinforced the idea of American exceptionalism and the notion that the United States had a responsibility to promote democracy and oppose tyranny in the world. The war also led to a reassessment of American isolationism, with some advocating for greater engagement in international affairs and the establishment of international organizations to prevent future conflicts.

League of Nations: The United States played a leading role in the creation of the League of Nations, an international organization aimed at preventing future wars. However, the US Senate ultimately rejected the Treaty of Versailles, which established the League, due to concerns over the country's sovereignty and the potential entanglement in European disputes.

Postwar Isolationism: In the aftermath of World War I, there was a strong public sentiment in favor of returning to isolationist policies. The United States withdrew from Europe and reduced its military presence overseas. However, the rise of fascism in Europe and the aggression of Japan in the Pacific ultimately led to the outbreak of World War II, once again drawing the United States into global conflicts.