Joseph Smith, Jr. was the American religious figure who founded the Latter Day Saint movement, also known as Mormonism. Smith's followers declared him to be the first latter-day prophet, whose mission was to restore the original Church of Jesus Christ, said to have been lost soon after the death of the Apostles which caused an apostasy. This restoration included the establishment of the Church of Jesus Christ of Latter Day Saints, the priesthood authority, and the publication of the Book of Mormon and other new scriptures. As a leader of large settlement communities, Smith also was recognized as a political and military leader in the American Midwest.