FLDS-Their Roots

Joseph F. Smith, the Mormons 6th prophet, was under tremendous pressure to put an end to the Mormon church's polygamous activities which was declared illegal by the US government in 1874-the Poland Bill. Not only did Reed Smoot counsel him to stop polygamy, the church attorney Franklin S. Richards did likewise. Richards informed Smith that some sort of declaration be written to show that the church was now anti-polygamous.
As a result of the pressure from Smoot, Richards and others, Joseph F. Smith issued a Manifesto to the Mormon community. Not only did it uphold the first Manifesto from Woodruff, the 4th prophet, but there was a serious penalty for disobedience: "If any officer or member of the church shall assume to solemnize or enter into any such marriage he will be deemed in transgression against the church, and will be liable to be dealt with according to the rules and regulations thereof and excommunicated therefrom." (Joseph F. Smith, The Church of Jesus Christ of Latter-day Saints, Conference Report, April 7, 1904) Smith himself was in clear violation of both manifestos. He had six wives to himself, yet Smith's second manifesto marked the beginning of a separation within the church. Mormons continued with polygamous marriages that had been taken place in their temples, and had been published in the local paper as late as 1910.
The Mormon church struggled with getting the polygamous image removed from their church. Two of their own apostles were used as scapegoats by the LDS authorities to protect that image. This act was part of Mormons assimilation into mainstream society. "LDS leaders subsequently resorted to what has become a hallmark of Mormonism-revision of history. Even before Musser's [A Fundamentalist publisher of the "Truth" magazine.] arrest, the article "Leaves From An Old Scrapbook" had been published in the church's Deseret News (June 1, 1940). It stated that polygamy began among the saints primarily because Mormons needed to rapidly increase their population in Utah to do the "work of subduing the deserts and building Zion." After that had been accomplished, said the article, plural marriage was no longer needed, and so it was discontinued." (One Nation Under Gods, Richard Abanes, pg 346, brackets added)
Not all Mormon believers accepted all the changes that were happening within the church. Future presidents of the LDS church continued to distance mainstream Mormonism away from polygamy, and after cohabitation became a felony, the church excommunicated large numbers of polygamists. Such action only gave birth to a full-blown movement of people committed to following the old ways. They are known as the Mormon Fundamentalists, or the FLDS = Fundamentalist Latter-day Saints.