First World War; Great War; WWI
World War I, also called First World War or Great War,
conflict that in 191418 embroiled most of the nations of Europealong with Russia, theUnited
States, theMiddle East, and other regions. The war pitted t
Lewis and Clark Expedition, (180406), U.S. military expedition, led by Capt. Meriwether
Lewis and Lieut. William Clark, to explore the Louisiana Purchase and the Pacific Northwest.
The expedition was a major chapter in the history of American exploration.
Alternative title: Second Indochina War
Vietnam War, (195475), a protracted conflict that pitted the communist government of
North Vietnamand its allies in South Vietnam, known as the Viet Cong, against the government of South
Vietnam and its principal al