On this day, April 12 …

1945: President Franklin D. Roosevelt dies of a cerebral hemorrhage in Warm Springs, Ga., at age 63; he is succeeded by Vice President Harry S. Truman.

Also on this day:

1861: The Civil War begins as Confederate forces open fire on Fort Sumter in South Carolina.

The Civil War begins as Confederate forces open fire on Fort Sumter in South Carolina. 1877: The catcher’s mask is first used in a baseball game by James Tyng of Harvard in a game against the Lynn Live Oaks.

The catcher’s mask is first used in a baseball game by James Tyng of Harvard in a game against the Lynn Live Oaks. 1934: “Tender Is the Night,” by F. Scott Fitzgerald, is first published in book form after being serialized in Scribner’s Magazine.

1955: The Salk vaccine against polio was declared safe and effective.

1961: Soviet cosmonaut Yuri Gagarin becomes the first man to fly in space, orbiting the earth once before making a safe landing.

Soviet cosmonaut Yuri Gagarin becomes the first man to fly in space, orbiting the earth once before making a safe landing. 1963: Martin Luther King Jr. is arrested and jailed in Birmingham, Ala., charged with contempt of court and parading without a permit. (During his time behind bars, King would write his “Letter from Birmingham Jail.”)

Martin Luther King Jr. is arrested and jailed in Birmingham, Ala., charged with contempt of court and parading without a permit. (During his time behind bars, King would write his “Letter from Birmingham Jail.”) 1988: The U.S. Patent and Trademark Office issues a patent to Harvard University for a genetically engineered mouse, the first time a patent is granted for an animal life form.

The U.S. Patent and Trademark Office issues a patent to Harvard University for a genetically engineered mouse, the first time a patent is granted for an animal life form. 1989: Boxing legend Sugar Ray Robinson dies in Culver City, Calif., at age 67.

Boxing legend Sugar Ray Robinson dies in Culver City, Calif., at age 67. 1989: Radical activist Abbie Hoffman is found dead at his home in New Hope, Pa., at age 52.

Radical activist Abbie Hoffman is found dead at his home in New Hope, Pa., at age 52. 1990: In its first meeting, East Germany’s first democratically elected parliament acknowledges responsibility for the Nazi Holocaust, and askes the forgiveness of Jews and others who suffered.

In its first meeting, East Germany’s first democratically elected parliament acknowledges responsibility for the Nazi Holocaust, and askes the forgiveness of Jews and others who suffered. 2006: In the Zacarias Moussaoui trial, the court listens to a recording of shouts and cries in the cockpit as desperate passengers twice charged hijackers during the final half hour of doomed United Flight 93 on 9/11.