In order to escape his abusive father, Brannan moved with his sister (Mary Ann) and her husband (Alexander) to Painesville, Ohio, when he was fourteen years old.

In the neighboring town of Kirtland, Ohio, Brannan, Alexander, and Mary Ann all joined the Church of Jesus Christ of Latter Day Saints in 1842.

[2]: 15  After his father's death, Brannan inherited a decent sum of money, bought himself out of his last year of his apprenticeship, and invested the rest in a patch of land near Cleveland.

After this tragedy, Brannan made his way back to the North, stopping in Indianapolis to promote a paper which ultimately failed, before he returned to Painesville.

[2]: 19–21 Once Brannan had returned to his sister's home, he renewed his religious convictions in the church and was called by the apostle Wilford Woodruff to serve a local mission in Ohio.

[2]: 38  Once he had sufficiently recovered he was again called to help the church, but this time as a printer in Connecticut working alongside the apostle William Smith.

While waiting in Connecticut to meet up with Smith, Brannan fell in love with Ann Eliza Corwin, whose mother took care of the visitors in the local boarding house.

[2]: 46 After the assassination of their leader, the Prophet Joseph Smith, rising hostilities, attacks on their homes and religious persecution, in the east, the Mormons decided to relocate their center from Nauvoo, Illinois, to the western region outside of the United States border.

The plans for the large exodus began and Mormon leadership moved westward, leaving Brannan the highest ranking religious leader in New York.

This information along with Commodore Stockton's quiet encouragement led Samuel Brannan to the idea of taking the Mexican port town of Yerba Buena.

Brannan's dreams of religious freedom and success were underway and after leaving Hawaii, the Brooklyn changed routes, landing on July 31, 1846, at Yerba Buena.

[1]: 237 After settling in Yerba Buena, Brannan consulted with natives who were familiar with the region and decided that the land down by the Sacramento River, which they named "New Hope", would be the next Nauvoo of the Mormons, but with real refuge and religious freedom.

[2]: 80  Brannan is often credited to have been the first to perform certain actions in the region: a non-Catholic wedding ceremony, the first to preach in English, and the first to set up a California public school and a flour mill.

[5] In June 1847, Brannan traveled overland to Green River, Wyoming, to meet with Brigham Young, the head of the Church of Jesus Christ of Latter-day Saints, who was leading the first contingent of Mormon pioneers across the plains to the Great Basin region.

He purchased pans for 20 cents each and resold them for $15 each, making $36,000 in nine weeks[6] In 1848, Brannan decided that he was going to use all of his resources in order to help build up California and its connection with the east.

He planned on building that connection through the California Star Express, which would deliver mail from San Francisco to Independence, Missouri, and had its first route on April 1, 1848.

He also acquired all of the remaining assets of the failed "New Hope" project and like many other Mormons at this time, found his focus had turned from LDS Church affairs to monetary gains.

[2]: 124 Using his profits and possibly the proceeds of tithing paid to him as an LDS Church representative, Brannan bought land from Sutter in the Sacramento area.

When Lyman arrived, Brannan was unable to account for the tithes that Brigham Young and other Mormons claimed were given to him or that he owed from his own personal income.

In 1851, after a series of sensational crimes in the area, he helped organize and was the first president of the San Francisco Committee of Vigilance, which functioned as a de facto police force with a propensity for hanging.

[11] In order to continue the settlement of the west, Brannan purchased California's first steam locomotive in an effort to hasten the building of the first western railroad.

[12] On August 25, 1851, he was disfellowshipped from the LDS Church for "a general course of unchristianlike conduct, neglect of duty, and for combining with lawless assemblies to commit murder and other crimes.

[17] American historian Hubert Howe Bancroft described Samuel Brannan's achievements saying: He probably did more for San Francisco and for other places than was effected by the combined efforts of scores of better men; and indeed, in many respects he was not a "bad man", being as a rule straightforward as well as shrewd in his dealings, as famous for his acts of charity and open-handed liberality as for in enterprise, giving also frequent proofs of personal bravery.