During the Civil War did the majority of the Saints lean toward the union or confederacy?
The slavery issue in the emerging States during the early days of the church was one of the fomenting factors for persecution against the Church. Prior to the admission of Missouri as a state, there were an equal number of free and slave States. As Missouri applied for Statehood in 1818, numbers of people from the South emigrated to Missouri with the intent of making it a slave state. Missouri was granted statehood on August 10, 1821.
On August 13, 1831, the Prophet, Joseph Smith received a revelation directing the Saints to gather together in the land of Missouri (D&C 62.) Most of the converts to the church, who were gathering to Zion at this time, were from the Northern states or from England, and both groups were opposed to slavery. This influx of people who were opposed to slavery alarmed the Missourians, and was the focal point of much conflict.
By the time of the Civil War, the early Saints had emigrated to the mountains of the West, where they were quite isolated from the conflict. However, the sympathies of the Mormons were generally opposed to slavery.