Hillary Clinton announced her candidacy for US President.
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The Battle of Fort Sumter in South Carolina between the United States and the Confederate States started the American Civil War.
Cardinal Bellarmine condemned Galileo for stating that the earth revolved around the sun.
The 'Twentieth Century Dinosaurs' exhibit opened at the Smithsonian Institution Museum of Natural History.
Rock Around The Clock by Bill Haley and His Comets was recorded.
Israeli Knesset chose April 13 as the official Holocaust Remembrance Day.
