Joseph Smith 1805-1844 Joseph Smith Jr., born on December 23, 1805, in Sharon, Vermont, was the fifth child of Joseph Smith and Lucy Mack. He had significant spiritual experiences that led him to his prophetic calling, including a vision of God the Father and Jesus Christ in 1820. He translated and published the Book of Mormon and established The Church of Jesus Christ of Latter-day Saints on April 6, 1830. As the leader of the Church, he called Apostles and other leaders, defined doctrines, and guided the community's growth in Ohio, Missouri, and Illinois. Tragically, Joseph Smith was martyred on June 27, 1844, in Carthage, Illinois.
Source: The Church of Jesus Christ of Latter-day Saints
https://www.churchofjesuschrist.org/study/history/topics/joseph-smith-jr?lang=eng allegedly writes a letter known as the "Happiness Letter", presenting arguments to justify plural marriage. The letter is addressed to Nancy Rigdon, the wife of Sidney Rigdon 1793-1876 Sidney Rigdon (1793-1876) was born in 1793 in Pennsylvania and married Phebe Brooks in 1820. A minister of the First Baptist Church of Pittsburgh, he converted to the Church of Jesus Christ of Latter-day Saints on November 8, 1830, after Oliver Cowdery 1806-1850 Oliver Cowdery was born on October 3, 1806. He served as a clerk, teacher, justice of the peace, lawyer, and newspaper editor during his lifetime. He acted as the principal scribe during the translation of the Book of Mormon in 1829. After, he received priesthood authority from angelic ministers. Cowdery was one of the Three Witnesses of the Book of Mormon plates and he played a crucial role in overseeing its publication. In April 1830, he led missionaries through Ohio to Missouri in 1830-1831. Later, he moved to Kirtland, Ohio, where he was elected justice of the peace in 1837. However, in 1838, he was excommunicated due to accusations against church leaders and rumors about Joseph Smith. In 1848, Cowdery was readmitted to the Church, but passed away in Richmond, Missouri on March 3, 1850.
Source: Joseph Smith Papers
https://www.josephsmithpapers.org/person/oliver-cowdery and Parley P. Pratt 1807-1847 Parley P. Pratt was born on April 12, 1807 in Burlington, New York. He married Thankful Halsey in 1827 and was baptized by Oliver Cowdery on September 1, 1830. Over the next three decades, Pratt was a dedicated writer and missionary, serving multiple missions in the United States, Canada, England, and Chile. He played a significant role alongside Joseph Smith in Missouri and was briefly imprisoned with him. He was ordained a member of the Quorum of the Twelve Apostles in 1835 and migrated with the Saints to Utah in 1847. While serving a mission in Arkansas, he was murdered outside the small town of Van Buren.
Source: Church of Jesus Christ
https://www.churchofjesuschrist.org/study/history/doctrine-and-covenants-historical-resources/people/bio-parley-p-pratt?lang=eng shared the Book of Mormon with him and Phebe. Rigdon served as a scribe for Joseph Smith's inspired Bible revision and was a member of the First Presidency of the early Church. Following Joseph Smith's death, Rigdon declined leadership, leading to his excommunication from the Church in 1844. Subsequently, he founded and led an independent Church organization until his passing in 1876.
Source: The Church of Jesus Christ of Latter-day Saints
https://www.churchofjesuschrist.org/study/history/topics/sidney-rigdon?lang=eng , a close associate of Smith. The letter has been the subject of much debate, and there is no consensus on whether or not it is authentic. Some scholars believe the letter is genuine, while others believe it is a forgery. If the letter is genuine, it would provide important insights into Smith's views on plural marriage. However, the lack of an image of the letter makes it difficult to verify its authenticity. info https://www.jstor.org/stable/10.5406/jmormhist.42.3.0094