Name one war fought by the United States in the 1900s.

World War II is indeed one of the wars fought by the United States in the 1900s, specifically from 1941 to 1945 following the attack on Pearl Harbor. This global conflict involved many nations and was pivotal in shaping the course of the 20th century, leading to significant changes in global politics, economics, and society.

The war saw the U.S. play a major role in the defeat of the Axis powers and was instrumental in the establishment of the United Nations, which aimed to foster international cooperation and prevent future conflicts. The impact of World War II on the United States was profound, leading to a post-war economic boom and the emergence of the U.S. as a prominent global superpower.

Looking at the other options, The Spanish-American War occurred in 1898 and thus falls outside the specified timeframe of the 1900s. The War of 1812 took place much earlier, and while the Vietnam War did occur in the 1900s, it is also important to note that World War II often receives more recognition due to its scale and the overall historical significance it carries.