In the United States Army, cavalry units were originally horse-mounted soldiers. After World War I, the cavalry began to transition to a mechanized method. During World War II, cavalry soldiers sometimes fought in tanks and sometimes on the ground. The last horse-mounted charge was made against the Japanese in the Philippines on January 16, 1942.
In 1950, the Cavalry Branch became part of the Armor branch, but the term was retained to designate certain units with historical lineage to cavalry units. During the war in Vietnam, units using helicopters were designed Air Cavalry while those in tanks were called Armored Cavalry. 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. The Cavalry branch was absorbed into the Armor branch in 1950, but the term "Cavalry" remains in use in the U.S. Army for certain armor and aviation units historically derived from cavalry units. Originally designated as United States Dragoons, the forces were patterned after cavalry units employed during the Revolutionary War. The traditions of the U.S. Cavalry originated with the horse-mounted force which played an important role in extending United States governance into the Western United States after the American Civil War. Immediately preceding World War II, the U.S. Cavalry began transitioning to a mechanized, mounted force. During World War II, the Army`s cavalry units operated as horse-mounted, mechanized, or dismounted forces (infantry). The last horse-mounted cavalry charge by a U.S. Cavalry unit took place on the Bataan Peninsula, in the Philippines. The 26th Cavalry Regiment of the Philippine Scouts executed the charge against Japanese forces near the village of Morong on 16 January 1942. The U.S. Cavalry branch was absorbed into the Armor branch as part of the Army Reorganization Act of 1950. The Vietnam War saw the introduction of helicopters and operations as an airborne force with the designation of Air Cavalry, while mechanized cavalry received the designation of Armored Cavalry. Today, the 1st Cavalry Division maintains a detachment of horse-mounted cavalry for ceremonial purposes.