THIS DATE IN HISTORY: APRIL 12

In 1606, England adopted the original version of the Union Jack.

In 1861, the Civil War began as Confederate forces fired on Fort Sumter in South Carolina.

In 1862, Union volunteers led by James J. Andrews stole a Confederate train near Marietta, Ga., but were later caught. (This episode inspired the Buster Keaton comedy "The General.")

In 1877, the catcher's mask was first used in a baseball game.

In 1945, Franklin Delano Roosevelt, the 32nd president of the United States, died of a cerebral hemorrhage at age 63.

In 1955, the Salk vaccine against polio was declared safe and effective.

In 1961, Soviet cosmonaut Yuri Gagarin became the first man to fly in space.

In 1983, Chicagoans went to the polls to elect Harold Washington the city's first black mayor.

In 1988, the U.S. Patent and Trademark Office issued a patent to Harvard University for a genetically engineered mouse, the first time a patent was granted for an animal life form.