David Rice Atchison (August 11, 1807 - January 26, 1886) was a Senator of the American Democratic Party from Missouri who was President Pro Tempore of the United States for six years. It's been claimed that for one day (March 4, 1849); following Taylor's refusal to be sworn in on a Sunday (Sabbath), that David Rice Atchison was Commander in Chief of the United States though no documentation has been found to support this hypothetical technicality. Both in his private life, and as a Senator Atchison was pro-slavery, and the owner of many slaves and a plantation. He was opposed to the Abolitionist movement and was a Border Ruffian leader during the Bleeding Kansas events.