Seventh Day German Baptists of the Ephrata Cloister in Pennsylvania (c. 1738), in a chapter entitled "Conrad Weiser Becomes A Priest After the Order of Melchizedek" Wallace says:
Out of the brain of Emanuel Eckering (Elimelech) there sprang that same year, 1738, the ingenious concept of the Baptism for the Dead. Persons who had died without the grace of total immersion might yet be saved if they were baptized by proxy. Peter Miller, who never lost his head amid all these insinuating mumeries, was against it; but [Conrad] Beissel [leader of the Seventh Day Baptists], ready as always to follow a religious wil-o'-the-wisp, set his seal upon it. Emmanuel Eckerling was the first to receive baptism in this kind. In a pool of the Cocalico, under Beissel's hands, he was immersed on behalf of his departed mother. The principle once accepted, the thing became popular, and the next world must soon have been swarming with souls so astonished to find themselves sainted by Cocalico immersion in abstentia. (p. 104)
Wallace cites as his source volume 1 of J. F. Sachse's The German Sectarians of Pennsylvania (Philadelphia, 1899), which adds that baptism for the dead was "practiced for many years" at Ephrata, that it outlived and went beyond that community and was accepted by people of other faiths. Sachse also claims that as late as the 1840s there were traditions of "children having become substitutes in Baptism for parents, or vice versa" (p. 366).
(Letters to the Editor, Frederick S. Buchanan, Dialogue: A Journal of Mormon Thought, vol. 24, no. 1, p. 9). (1)
-- During 1807
Charles Buck first publishes the popular 'A Theological Dictionary' in the U.S., later used by Joseph Smith. "BAPTISM FOR THE DEAD, a practice formerly in use, when a person dying without baptism, another was baptized in his stead; thus supposing that God would accept the baptism of the proxy, as though it had been administered to the principal. ... If it can be proved (as some think it can) that this practice was as early as the days of the apostle Paul" (2)
-- Apr 6, 1830
[Revelations] Fayette, New York. Doctrine and Covenants 22. New and everlasting covenant. Non-Mormon baptisms not recognized.
Book of Commandments Book B (1833).
Book of Commandments 23.
1835 Doctrine and Covenants 47.
Headings.... /BC 23 A Commandment unto the church of Christ, which was established in these last days, in the year of our Lord one thousand eight hundred and thirty: Given in Fayette, New-York, April, 1830, in consequence of some desiring to unite with the church without re-baptism, who had previously been baptized.
1835 D&C 47 Revelation to the church of Christ, which was established in these last days, in the year of our Lord one thousand eight hundred and thirty: Given April, 1830 in consequence of some desiring to unite with the church without re-baptism, who had previously been baptized.
1981 Doctrine and Covenants Revelation given through Joseph Smith the Prophet, at Manchester, New York, April 1830. HC 1:79-80. This revelation was given to the Church in consequence of some who had previously been baptized desiring to unite with the Church without rebaptism. (3)
-- Apr 16, 1830
Revelation, 16 April 1830 [D&C 22]
24 Commandment AD 1830 A Revelation given to Joseph the Seer Some were anxious to Join the Church [DEL:they] without Rebaptism & Joseph enquired of the Lord & he received as follows A commandment unto the Church of Christ which was established in these [DEL:day] last days one thousand eight hundred & thirty on the forth month & on the sixth day of the month which is called April Behold I say unto you that all old covenants have I [DEL:called] caused to be done away in this thing & this is a New & an everlasting covenant even [DEL:wherefore] the same which was from the begining wherefore although a man shouldest be baptized an hundred times it availeth him nothing for ye cannot enter into the strait gate by the law of Moses neither by your dead works for it is because of your dead works that I have caused this last covenant & this church to be built up unto me even as in days of old wherefore enter ye in at the [DEL:at] gate as I have commanded & seek not to Council your Go
-- Feb 16, 1832
Section 76, Place: Hiram, Portage County, Ohio.
Historical Note: After returning to Hiram from the Amherst conference, Joseph Smith and Sidney Rigdon resumed the translation of the New Testament. Section 76 was received while they were translating John 5:29. Known as "The Vision," this section is of major doctrinal importance. ...
The heathen of ages that never had hope,.
And those of the region and shadow of death,.
The spirits in prison, that light has brought up.
55. To spirits in prison the Savior once preachd,.
And taught them the gospel, with powers afresh;.
And then were the living baptizd for their dead,.
That they might be judgd as if men in the flesh.
56. These are they that are honrable men of the earth;.
Who were blinded and dupd by the cunning of men:... (5)
1 - "Conrad Weiser: Friend of Colonists and Mohawk" (Philadelphia: University of Pennsylvania Press, 1945), Paul A. Wallace.
2 - Grunder, Rick, Mormon Parallels: A Bibliographic Source
3 - Kenny, Scott; Saints Without Halos, 'Doctrine and Covenants,' http://saintswithouthalos.com/s/_dc.phtml
4 - Book of Commandments and Revelations (Revelation Book 1) http://bit.ly/manuscript-revelations
5 - Cook, Lyndon, Revelations of the Prophet Joseph Smith: A Historical and Biographical Commentary of the Doctrine and Covenants, http://amzn.to/RevelationsofJosephSmith
LDS History Chronology: Unconventional Baptism
Mormon History Timeline: Forms of Rebaptism in LDS History