1A

After Joseph Smith's death, schisms threatened to rend the early Mormon church.

• Brodie, 398.

2A

Smith had not explicitly chosen a successor, although there is evidence that he had blessed his son Joseph III with the understanding that he would eventually succeed him.

• Ostlings, 42.
• The church had published a revelation in 1841 stating, "I say unto my servant Joseph, In thee, and in thy seed, shall the kindred of the earth be blessed." Covenant 107:18c and this prophecy was interpreted as endorsing the concept of Lineal Succession.
• Evidence also suggests that Smith set apart his son as his successor at other places, including Liberty (Joseph Smith III and the Restoration (Herald House, 1952), 13.) and Nauvoo. (Autumn Leaves, 1: 202).
• Indeed, as late as 1860, Brigham Young assured the bulk of Smith's followers that young Joseph would eventually take his father's place. (Journal of Discourses, 8: 69.)

•  Violates Wikipedia: Synthesis off-site: Do not put together information from multiple sources to reach a conclusion that is not stated explicitly by any of the sources.
  
  The sources provided do not support the assertion that Brigham stated that "young Joseph would eventually take his father's place."
• Brigham said,

What of Joseph Smith's family? What of his boys? I have prayed from the beginning for sister Emma and for the whole family. There is not a man in this Church that has entertained better feelings towards them. Joseph said to me, "God will take care of my children when I am taken." They are in the hands of God, and when they make their appearance before this people, full of his power, there are none but what will say—"Amen! we are ready to receive you."

The brethren testify that brother Brigham is brother Joseph's legal successor. You never heard me say so. I say that I am a good hand to keep the dogs and wolves out of the flock. I do not care a groat who rises up. I do not think anything about being Joseph's successor.Brigham Young, Journal of Discourses 8:69.

• Brigham's comment "we are ready to receive you" applied to all of Joseph's children, not just Joseph Smith III.
• Ostlings, Mormon America: The Power and the Promise (p. 42) state: "There is historical evidence that Joseph Smith blessed his son, Joseph III, with the intention that the boy would become his successor, but the boy was only eleven when his father was murdered." The endnotes, however, do not provide any supporting references for this claim.
•  References not included in the Wikipedia article
  Brigham was quite adamant that Joseph Smith III would not lead the church:

Joseph Smith that now is living in the state of Illinois, the son of Joseph the Prophet, will never lead the Latter-day Saints: he may lead apostates.
Brigham Young Addresses, Given in SLC Bowery, 7 October 1863, HDC, Ms d 1234, Box 49 fd 11

• See: Primary sources/Brigham Young/7 October 1863‎
• See: Succession in the Presidency of the Church

3A

But the boy was only eleven when his father was murdered. William Clayton, one of Smith's confidants and secretaries, declared that Smith had recently said that if he and Hyrum were removed, a younger brother, Samuel H. Smith should be his successor.

• Clayton Journal, July 12, 1844, quoted in Bushman (2005), 555. Because of the long controversy between the Utah and Missouri churches, the succession question has been extensively debated in both popular and scholarly publications.

4A

Samuel died a month later.

• Bushman (2005), 555.

5A

The "unstable character" of another brother, William Smith, prevented him from becoming a serious contender.

• ^[1]

6A

A fairly recent convert, James J. Strang, produced a counterfeit letter from Smith commissioning him to lead the church.

• Bushman (2005), 555. Strang also claimed he had been ordained by an angel.

7A

Although Strang's previous relationship with Smith and the Saints had been minimal, he was able to produce revelations with a seerstone and discovered another set of supernatural writings, the Voree Plates. Strang attracted two thousand followers, including William Smith, Martin Harris, and John C. Bennett; but Strang was assassinated in 1856 after he began to practice polygamy.

• <ref name="Bushman 2005, 556">Bushman (2005), 556.

8A

As the senior surviving member of the First Presidency, Sidney Rigdon had a strong claim to leadership. Although his relationship with Smith had been uneven since 1839, on hearing of his assassination, Rigdon rushed from Pittsburgh to Nauvoo.

• Bushman (2005), 556. After his imprisonment in Liberty jail, Rigdon was plagued by ill health; then in 1842 after breaking with Smith over his unsuccessful proposal of plural marriage to Rigdon's daughter Nancy, Smith nearly had him removed from the First Presidency. But after William Law's defection, Rigdon was welcomed back.

9A

At an August 8 meeting of the Nauvoo congregation, Rigdon claimed he had had a vision in which the Lord had made him the "Guardian" of the late prophet. At the same meeting Brigham Young proposed that the Quorum of the Twelve, of which he was the senior member, should lead the church.

• ^[2]

10A

The experienced Young and the Twelve were easily sustained as the Presidency.

• Bushman (2005), 557. Rigdon retreated to Pennsylvania where he founded churches that only briefly survived his death in 1876.

11A

Later a legend grew that when Young rose to speak, members of the audience were struck by the similarity between his voice and mannerisms and those of the late prophet.

• Bushman (2005), 557. The Times and Seasons reported that just before the sustaining vote at the afternoon session of the August meeting, "every Saint could see that Elijah's mantle had truly fallen upon the 'Twelve.'" Although the church newspaper did not refer to Young specifically for the "mantle" experience, on 15 November 1844 Henry and Catharine Brooke wrote from Nauvoo that Young "favours Br Joseph, both in person, manner of speaking more than any person ever you saw, looks like another." Five days later Arza Hinckley referred to "Brigham Young on [w]hom the mantle of the prophet Joseph has fallen."Quinn, D. Michael (1994), The Mormon Hierarchy: Origins of Power 166

12A

Young, who lacked the charisma of Smith, was an even greater motivator of men. As Arrington and Bitton have written, he had "a compulsion to organize and do."

• <ref name="Arrington & Bitton, 85">Arrington & Bitton, 85.

13A

In the next eighteen months, the Nauvoo Mormons accomplished as much work on the temple as had occurred in the previous three years under Smith.

• ^[3]

14A

But by that time, persecution of the Saints resumed in earnest. The state legislature revoked the Nauvoo city charter, and there were barn-burning and crop-burning attacks on outlying settlements.

• Arrington & Bitton, 94.

15A

It was clear that Saints would have to leave Illinois. By the fall of 1846, Nauvoo was a virtual ghost town.

• Arrington & Bitton, 96.

1A

At the beginning of the twenty-first century, adherents of the denominations originating from Joseph Smith's teachings numbered perhaps as many as thirteen or fourteen million. The Church of Jesus Christ of Latter-day Saints is the largest with a self-reported membership of over thirteen million.

• http://www.deseretnews.com/article/1,5143,695242682,00.html. "Addressing the New Mission Presidents Seminar on June 24, President Hinckley announced that LDS Church membership had reached 13 million." More members now reside outside than in the United States. The first million-member milestone was reached in 1947, the second in 1963.Statistical Report, 2007, off-site

2A

The second largest is the Community of Christ, formerly known as the Reorganized Church of Jesus Christ of Latter Day Saints (RLDS), with about 250,000 members. Other groups which follow Smith's teachings have memberships numbering from dozens to tens of thousands.

• Steven L. Shields, Divergent Paths of the Restoration: A History of the Latter Day Saint Movement (Los Angeles: 1990).