Miller began to preach in 1831. Based on Daniel 8-9, Miller counted 2300 years from the time Ezra was told Jesus Christ could return to Jerusalem to reestablish the Temple. The date of this event was calculated to be 457 B.C Thus, 1843 became the date of Christ's return. As the appointed year grew closer, Miller specified 21 March 1843 to 21 March 1844 as his predicted climax of the age. The date was revised and set as 22 October 1844.
Failure of this event has come to be know as the Great Disappointment. It is estimated that the Millerites, as they came to be known, numbered nearly 50,000. Miller recorded his personal disappointment in his memoirs: ''Were I to live my life over again, with the same evidence that I then had, to be honest with God and man, I should have to do as I have done I confess my error, and acknowledge my disappointment (Memoirs of William Miller, Sylvester Bliss, p. 256).