Which war was fought by the United States in the 1900s?

World War II is indeed a conflict that was fought by the United States in the 1900s. This global war lasted from 1939 to 1945 and involved many of the world's nations, including the United States, which entered the war after the attack on Pearl Harbor in December 1941. The significance of World War II extends far beyond American borders, as it resulted in vast geopolitical changes worldwide and laid the groundwork for the modern international order.

By identifying World War II as the correct answer, it's important to highlight that the other options reflect wars that occurred either prior to the 1900s or in different contexts. The Civil War, for example, took place from 1861 to 1865, fundamentally shaping the nation’s history but well before the 20th century. The War of 1812 occurred in the early 19th century, specifically between 1812 and 1815, and dealt mainly with maritime issues and territorial disputes between the United States and Great Britain. The Spanish-American War, while occurring in 1898, is just outside the specified century by only a couple of years, making it less relevant when focusing specifically on the 1900s.

World War II stands out as a significant