But the same causes which proved disastrous to the settlements in Ohio and Missouri soon began to operate in Illinois. The people were outraged at the immoral doctrines of the new sect, and alarmed at the arrogant defiance of civil authority by its spiritual and temporal head. Finally an act of violence under Smith’s authority led to his arrest and that of his brother Hyrum, and their confinement in the Carthage jail, under guarantee of safety by the Governor of the State. But a mob was organized which overbore the civil authority, broke into the jail, and slew the brothers in cold blood. For the future development of the sect, this was the most fortunate event in its history. It set the seal of martyrdom upon the founder of the church; it healed internal dissensions; it intensified the high purpose to succeed; and finally it opened up the career of the one man who above all others was qualified to carry the movement to success. This was that astute and gifted leader of men, prophet Brigham Young. [Sidenote: NO ABIDING PLACE.] [Sidenote: A FINAL HOME.] It was now apparent that there was no abiding place for the church upon the soil of the United States, and it was necessary to look beyond. From the narratives of those who had visited the regions west of the Rocky Mountains, Young determined to lead his people to the valley of the Great Salt Lake, at this time a possession of the Mexican Republic. In that remote and benighted wilderness his people could at least have freedom from persecution, for the civil authority of Mexico could scarcely reach so far. The movement was decided upon. Smith had been killed in June, 1844, and the general exodus began in the spring of 1846. In July, 1847, Young laid the foundation of the final home of his people on the shores of the Great Salt Lake. In the course of this movement large bodies of Mormons remained encamped for long periods on both shores of the Missouri near Council Bluffs and Omaha. This situation became the great rendezvous for the expeditions before starting across the plains, and it was here that the Mormons came into relation with the steamboat traffic of the Missouri. Large quantities of freight and great numbers of passengers were brought up and disembarked here. The _Saluda_, whose tragic fate we have elsewhere described, was loaded with Mormons. In 1851 the steamer _St. Ange_ carried up two hundred of these people, and the _Sacramento_ four hundred. Many other boats, for fully a decade after 1846, brought up passengers and freight destined to the distant colony in the heart of the Rocky Mountains. [Sidenote: WAR WITH MEXICO.]