It began with a peaceful “Sit-In” April 3 1963
The Inca Empire, or Inka Empire (Quechua: Tawantinsuyu), was the largest empire in pre-Columbian America. The administrative, political and military center of the empire was located in Cusco in modern-day Peru. The Inca civilization arose from the highlands of Peru sometime in the early 13th century.
D. Fear of communism spreading to many Asian countries
"The following month, Germany sunk four more U.S. merchant ships. ... On April 6, 1917, the United States entered World War I. Get a firsthand look at how a new breed of weapons like WMDs, submarines, armored tanks and air attacks changed modern warfare forever in WWI: The First Modern War"