The geographical position of Missouri is such, that if thrown into the scale, she would weigh heavily either for or against the Union. When the war broke out her people were divided, though the majority were believed to be loyal to the Constitution; and when the Governor refused to meet the requisition of the President for troops to sustain the national flag, Hon. Frank P. Blair and other prominent citizens of the State, replied, on their personal responsibility, that the quota of four regiments should be raised, without either the aid of the Governor or his consent. In order to give character and legality to their proceedings, and to guard against the power of the State rulers, Captain Nathaniel Lyon, of the United States army, then in command of the Arsenal at St. Louis, was directed by the Government, on the 30th of April, to enrol in the military service of the United States, from the loyal citizens of the city and vicinity, 10,000 men, for the purpose of maintaining the authority of the Government—for the protection of the peaceable inhabitants of Missouri, and to guard against any attempt on the part of the secessionists to gain military possession of the city of St. Louis. Captain Lyon was also instructed that this force should be disbanded when the emergency ceased to exist. Recruiting offices were opened, under his direction, the loyal citizens were prompt in their response, and on the 2d of May, Colonel F. B. Blair announced that the four regiments called for from that State had been enrolled, equipped, and mustered into service. The Police Commissioners of St. Louis had called upon Captain Lyon, on the opening of recruiting stations, and demanded the removal of the United States troops from all places and buildings occupied by them in the city outside of the Arsenal grounds, but he declined compliance, and the Commissioners referred the matter to the Governor and the Legislature, alleging that such occupancy was derogatory to the Constitution of the United States—that Missouri had “sovereign and exclusive jurisdiction over her entire territory,” and had delegated a portion of that territory only (the Arsenals, etc.,) to the United States for military purposes. CAPTURE OF CAMP JACKSON. In response to Governor Jackson’s order directing the military in certain districts to go into encampments for the purpose of improvement in the tactics of war, a camp had been formed at Lindell’s Grove, in the suburbs of St. Louis, called “Camp Jackson.” On the 4th of May it was inaugurated, under the charge of General D. M. Frost, and within a week numbered 800 men. Having received intelligence that it was the purpose of Captain Lyon to break up this encampment, General Frost addressed him a letter, dissuasive in its tone—disclaiming any intention on the part of himself and men of hostility to the Government, and containing an offer to preserve the public peace and guard the property of the United States.