The Civil War began when Fort Sumter was attacked.
James J. Andrews led the raiding party that stole the Confederate locomotive "The General," inspiring the 1926 Buster Keaton movie.
President Franklin Roosevelt died.
The polio vaccine of Dr. Jonas Salk was called "safe, effective, and potent."
Soviet cosmonaut Yuri A. Gagarin became the first human in space and also the first human to orbit the earth in a spacecraft.
Harold Washington was elected Chicago’s first African-American mayor.