Background: The United States Cavalry, or U.S. Cavalry, was the designation of the mounted force of the United States Army from the late 18th to the early 20th century. Significant numbers of horse mounted units participated in early foreign conflicts in the Spanish–American War of 1898, and in the Western Front battlefields of Europe in World War I (1917–1918), although numbers and roles declined. Immediately preceding World War II (1941–1945), the U.S. Cavalry began transitioning to a mechanized, mounted force. The Cavalry branch became the Armor branch with tanks in 1950, but the term "Cavalry" such as "armored cavalry" remains in use in the U.S. Army for mounted (ground and aviation) reconnaissance, surveillance, and target acquisition (RSTA). The 1st Cavalry Division is the only active division in the United States Army with a cavalry designation. The division maintains a detachment of horse-mounted cavalry for ceremonial purposes.