The Illinois legislature voted to repeal the Nauvoo charter and called for the immediate disbanding of the Nauvoo Legion. But in defiance of that order, the Saints maintained the legion so as to be able to defend and police the city. A group of young men and boys known as the Whistling and Whittling Brigade also drove unwanted characters out of the city by following them around whistling and whittling until they were intimidated into leaving.
When the Church's enemies saw that they had not dispersed after the death of their charismatic leader, they renewed their attempts to drive them out of Illinois. When a mob of 300 men began burning some of the Mormons' outlying homes and farms, Brigham Young dispatched a posse to drive them off. Porter Rockwell accomplished this by killing the mob's leader with his rifle.
At this time, with war threatening to erupt, the United States federal government issued an indictment against Brigham Young and eight others among the Twelve Apostles on charges of instigating and harboring a counterfeiting operation. When government officials arrived to arrest Young, he deceived them by having another man pose as him while Young himself fled and went into hiding.
Church leaders then caught many of the Saints off-guard by publishing an announcement that all Church members were to sell their property, pack up their belongings, and leave Nauvoo behind. The Church would be seeking out a new gathering place west of the Rocky Mountains—outside the borders of the United States, in the Republic of Mexico—where "where bigotry, intolerance and insatiable oppression" would become a thing of the past.
Like others who rejected the doctrine of plural marriage, the prophet's widow Emma Smith chose to remain in Nauvoo with her five children and the prophet's aged mother Lucy Mack, despite having little means to provide for her family. Having suffered enough from her husband having taken so many additional wives, Emma Smith refused to discuss the matter of plural marriage ever again.
• Church History In The Fulness Of Times Student Manual, (2003), 286–296
• Jones, Gracia N. "My Great-Great-Grandmother, Emma Hale Smith". Ensign Magazine of the LDS Church, August 1992.
• Plural Marriage in Kirtland and Nauvoo, The Church of Jesus Christ of Latter-Day Saints. 22 October 2014.
In 1847, Emma Smith married again, to a man named Lewis Bidamon who did not affiliate with any church. They remained together up to her death at age 75 in 1879. Her nurse reported that on her deathbed, Emma had a vision of Joseph Smith holding their son Don Carlos who had died when he was 18 months old. The prophet stood next to Jesus Christ and said to her, "Emma, come with me, it is time for you to come with me."
When the prophet's namesake Joseph Smith III came of age, he was made the president of the Reorganized Church of Jesus Christ of Latter Day Saints, which had been started by men who stayed behind in Nauvoo when the Church moved West. Their headquarters was later moved to Zion—which is to say, Independence, Missouri. By 1975 this church had over 200,000 members, and remains active today under the name Community of Christ.
In February of 1846, Brigham Young led the journey of the Saints out of Nauvoo. But the hurriedness of their departure led to a lack of preparedness, and food supplies ran out within weeks. Many fell ill from the extreme cold, and pregnant women had to deliver their babies in makeshift camps where the infants suffered terribly from exposure. But Young noted that the Saints endured all these hardships without complaining.
In mid-April, in the Iowa Territory, the Saints founded a waystation they named Mount Pisgah. There they enclosed, planted, and farmed several thousand acres. The population at Mount Pisgah rose as high as 3,000, and Brigham Young celebrated his 45th birthday there.