Union cause in Missouri is to be attributed.  For a time St. Louis was the theatre of action.  The police commissioners, backed by Governor and Legislature, in the demanded the removal of the Union troops from the grounds of the arsenal, claiming it as the exclusive property of the State, and asserting that the authority usurped by the general government as but a partial sovereignty, and limited to the occupation, for purposes exclusively military, of the certain tracts of land now pending in this novel court of chancery.  This highly enigmatical exposition of State rights, pompous and inflated though it was, failed to convince or convert Captain Lyon, who, being unable to detect, in his occupancy of the arsenal, any exaggeration of the rights vested by the Constitution in the general government, declined to abandon his post, and proceeded to call out the Home Guard, then awaiting the arrival of General Harney, and temporarily under his command.  His little army of ten thousand men was then drawn up upon the heights commanding Camp Jackson, then occupied by the Missouri militia under Col.  Frost, whoso command had been increased by the addition of numerous individuals of avowed secession principles.  Uninfluenced by the reception of a note from this officer asserting his integrity and his purpose to defend the property of the United States, and disavowing all intention hostile to the force at the arsenal, Captain Lyon replied by a peremptory summons for an unconditional surrender.  He found it incredible that a body assembled at the instigation of a traitorous governor, and acting under his instructions and according to the ‘unparalleled legislation’ of a traitorous legislature, receiving under the flag of the Confederate States munitions of war but lately the acknowledged property of the general government, could have any other than the as most unfriendly designs upon its enemies.  The force of Camp Jackson (which notwithstanding its professed character, boasted its streets Beauregard and Davis) being numerically inferior, and perhaps not entirely prepared to do battle for a cause whose legitimacy must still have been a question with many of them, decided, after a council of war, to comply with the demands of Capt.  Lyon, and became his prisoners.  A few days afterward General Harney arrived, and Captain Lyon was elected Brigadier General by the 1st Brigade Missouri Volunteers.

Convinced of the imminence of the crisis and the peril of delay, Gen. Lyon immediately commenced active operations against the secessionists at Potosi, and ordered the seizure of the steamer which had supplied the offensive army with material of war from the United States property at Baton Rouge.  In the meantime, Gen. Harney, with a culpable blindness, had made an extraordinary arrangement with Gen. Price, by which he pledged himself to desist from military movements so long as the command of Gen. Price was able to preserve order in the State.  Upon his removal by the authorities at Washington,