George M. Cohan's song "Over There" captured the patriotic mood of the time
Foreign affairs (relationships with other countries) took up a great deal of President Woodrow Wilson's attention. In Europe, there was the outbreak of World War I, also known as the Great War, in 1914, and in Mexico, there was the Mexican Revolution. Although at first Americans did not want to get involved, they supported the Allies in their fight against the Central Powers. Finally, the U.S. entered the war in 1917. The war concluded in 1918 and the Treaty of Versailles was signed in 1919. The Allied Powers of the U.S., Great Britain, Japan, Italy, Russia, France, Belgium, Serbia and Montenegro had been victorious.
Back at home, young people were tired of the war. Women exercised their newly found freedom (having won the right to vote in 1920) and many whites took up an interest in African American culture. Harlem nightclubs thrived, spotlighting numerous artists such as jazz musicians Louis Armstrong and Duke Ellington.