Hillary Clinton announced her candidacy for US President.
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The 'Twentieth Century Dinosaurs' exhibit opened at the Smithsonian Institution Museum of Natural History.
Project Starshot was announced by Yuri Milner, Stephen Hawking, and Mark Zuckerberg.
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.
Shapur I became co-emperor of the Sasanian Empire with his father Ardashir I.
