What is one war fought by the United States in the 1900s?

World War II is indeed a significant conflict fought by the United States in the 1900s, specifically from 1941 to 1945 after the attack on Pearl Harbor. This global war involved multiple nations and had profound impacts on international relations, military strategy, and the course of history. It is characterized by major events such as the D-Day invasion, the use of atomic bombs in Hiroshima and Nagasaki, and the eventual defeat of Axis powers including Germany, Italy, and Japan.

In contrast, while the Civil War was pivotal in American history, it occurred from 1861 to 1865, well before the 1900s. The Spanish-American War took place in 1898 and, although it marks the emergence of the U.S. as a world power, it does not fall within the 1900s timeframe. The Mexican-American War occurred from 1846 to 1848, long before the 20th century. Thus, World War II is the only option that aligns with the criteria of wars fought by the United States during the specified century.