Today:
966: Mieszko I, the ruler of Poland, converts to Christianity, an event often cited as the founding of the Polish state.
1471: The Battle of Barnet takes place during the Wars of the Roses, resulting in a decisive victory for the Yorkist King Edward IV.
1775: The first abolitionist society in North America, the Society for the Relief of Free Negroes Unlawfully Held in Bondage, is organized in Philadelphia.
1828: Noah Webster copyrights the first edition of his American Dictionary of the English Language.
1865: President Abraham Lincoln is shot by John Wilkes Booth at Ford’s Theatre; he died the following morning.
1890: The Pan-American Union is established during the First International Conference of American States.
1912: The British passenger liner RMS Titanic strikes an iceberg in the North Atlantic and begins to sink.
1935: The Black Sunday dust storm, one of the most severe in the history of the Dust Bowl, sweeps across the Oklahoma and Texas panhandles.
1986: U.S. warplanes launch Operation El Dorado Canyon, bombing targets in Libya in response to a discotheque bombing in West Berlin.
2003: The International Human Genome Sequencing Consortium announces the successful completion of the Human Genome Project.