Who is Hyrum Smith from No Man Knows My History: The Life of Joseph Smith and what is their importance?

Hyrum Smith is Joseph Smith's older brother and confidant. Hyrum stood by Joseph in all things. Though he never was appointed to positions of high authority, he was always beside his brother in times of trouble. Hyrum spent time in jail with his brother nearly every time he was sent to jail. It was Hyrum, among others, who believed that Joseph would be safe in the hands of Governor Ford. Hyrum was the first to die at Carthage jail when the mob stormed the jail cell, killing Hyrum and the prophet, Joseph Smith.