What is the history of David Rice Atchinson and what are the revelant aspects of his life?

David Rice Atchinson was a United States Senator from
Missouri and for a time President prop tempore of the Senate. He supported slavery
apologetically, and supported the annexation of Texas as a slave state and abolition of
that portion of the Missouri Compromise which prohibited slavery in the territories
above the Missouri line. Rather, he proposed that the slavery issue be settled by
popular sovereignty. He encouraged Stephen Douglas of Illinois to introduce the Bill
into the Senate which later became the Kansas-Nebraska
Act.

Atchinson fought briefly on the Confederate side in
the Civil War as a general in the Missouri State Guard; however after Union forces
gained control of Missouri in 1862, he resigned his commission and retired to his
farm.

Among the more interesting aspects of his political
career is that he claimed to be President of the United States for one day. The term of
James K. Polk as President expired at noon on March 4, 1849, a Sunday. His successor,
Zachary Taylor, refused to be inaugurated on a Sunday; and Taylor's Vice President
elect, Milliard Fillmore was also not inaugurated. Under the then Presidential
succession act, Atchinson, as Senate president pro tempore, became Acting Vice
President; and in the eyes of some, President of the United States, albeit for only one
day. Taylor was inaugurated on Monday, March 5.