Which global conflict dominated the 1910s in which the United States emerged as a major world power after intervention?

• A. World War II.
• B. World War I.
• C. The Korean War.
• D. The Spanish-American War.

Answer: (B)

During the 1910s, a global conflict dominated international affairs: World War I. The United States initially stayed neutral, but after German submarine warfare and other provocations threatened American interests, it entered the war in 1917. Mobilizing a massive army and leveraging its industrial capacity, the U.S. helped tip the balance in favor of the Allies and played a leading role in shaping the postwar settlement. This involvement marked the United States’ emergence as a major world power on both the military and diplomatic stages. The other conflicts listed occurred outside the 1910s—World War II in the 1940s, the Korean War in the 1950s, and the Spanish-American War in 1898—so they don’t fit the timeframe described.