The death of Joseph Smith's last surviving plural wife, Mary E. Rollins Lightner. She helped save the still-unbound Book of Commandments from the printing office set afire by a mob in 1833. She witnessed the adoption of the 1835 D&C, which prohibited polygamy, and became a secret plural wife of Joseph Smith at Nauvoo while still living with her non-Mormon husband. She moved with her husband to Utah where she also witnessed polygamy's accepted practice in Mormon society, its "underground" survival despite federal raid, its official prohibition by the 1890 Manifesto, the renewal of authorized polygamy despite official denials, the Second Manifesto and disciplining of two apostles for post-Manifesto polygamy, the general disfavor of plural marriage by "modern" Latter-day Saints, and even the early stages of Fundamentalist polygamy.
[The Mormon Hierarchy - Extensions of Power by D. Michael Quinn, [New Mormon History database ( http://bit.ly/NMHdatabase )]]