March 4, 1519: Hernando Cortez and 509 soldiers arrive at Veracruz to begin their brutal conquest of the Aztec people. His arrival coincides with an Aztec prophecy that Quetzalcoatl, a major god in Aztec culture, would return.
March 4, 1962: A small nuclear reactor is activated to provide power for the U.S. Antarctic research base at McMurdo Station (at right, in 2005). Plagued by minor leaks and accidents, the reactor is dismantled 11 years later.
March 4, 1965: A natural gas pipeline explodes near Natitoches, La., killing 17 people. The tragedy is credited with inspiring the passage of the Natural Gas Pipeline Safety Act three years later.
Photo: ZUMA Press