Vietnam was America's longest war until Afghanistan. French colonial rule → Ho Chi Minh's independence movement → U.S. intervention based on containment/Domino Theory. Divided the nation more than any event since the Civil War.
AP Exam Focus (KC 8.1.I / 8.1.II): Key topics: (1) Gulf of Tonkin Resolution as "blank check," (2) Credibility gap / media's role, (3) Tet Offensive as TURNING POINT, (4) Draft inequities (class-based), (5) Kent State as government force against citizens, (6) Pentagon Papers / Watergate connection, (7) War Powers Act (1973) as Congress reasserting authority, (8) Vietnam Syndrome — lasting reluctance toward military intervention.