Excerpts from Books and Wikipedia
"The Millerites later settled on October 22, 1844 as the day He would return, and this date became the day of the "Great Disappointment." [The Burned-Over District by Whitney R. Cross] "In Persia an even more obviously nationalist and revolutionary heterodoxy, the bab movement of Ali Mohammed, arose in the 1840s. . . . William Miller, the founder of the Seventh Day Adventists in the USA, predicted it [end of the world] for 1843 and 1844, by which time 50,000 were said to follow him and 3,000 preachers to back him." [Hobsbawm: Revolution, p. 225-29] "Expectations of Christ's imminent miraculous return by no means appealed solely to the unlettered. Prominent intellectuals like Timothy Dwight, president of Yale, and John Livingston, president of Rutgers, shared them. In 1827, a conference at Albury Park in England, attended by many leading clerics and respectable laymen, applied methods of calculation similar to Miller's and concluded that the judgment day was close at hand." [Howe: What Hath God Wrought, p. 290] See the Period: William Miller.