In the 1994 film “Legends of the Fall,” the sons of Anthony Hopkins’ character, Col. William Ludlow, all enlist to fight in what war?

In the 1994 film “Legends of the Fall,” the sons of Anthony Hopkins’ character, Col. William Ludlow, all enlist to fight in what war?

American Revolution
Mexican-American War
U.S. Civil War
World War I
World War II

The correct answer is World War I