The bombardment of Fort Sumter changed the political situation as if by magic. There was no longer room for doubt, hesitation, concession, or compromise. Without awaiting the arrival of the ships that were bringing provisions to Anderson's starving garrison, the hostile Charleston batteries had opened their fire on the fort by the formal order of the Confederate government, and peaceable secession was, without provocation, changed to active war. The rebels gained possession of Charleston harbor; but their mode of obtaining it awakened the patriotism of the American people to a stern determination that the insult to the national authority and flag should be redressed, and the unrighteous experiment of a rival government founded on slavery as its corner-stone should never succeed. Under the conflict thus begun the long-tolerated barbarous institution itself was destined ignobly to perish. On his journey from Springfield to Washington Mr. Lincoln had said that, devoted as he was to peace, he might find it necessary "to put the foot down firmly." That time had now come. On the morning of April 15, 1861, the leading newspapers of the country printed the President's proclamation reciting that, whereas the laws of the United States were opposed and the execution thereof obstructed in the States of South Carolina, Georgia, Alabama, Florida, Mississippi, Louisiana, and Texas, by combinations too powerful to be suppressed by the ordinary course of judicial proceedings, the militia of the several States of the Union, to the aggregate number of seventy-five thousand, was called forth to suppress said combinations and cause the laws to be duly executed. The orders of the War Department specified that the period of service under this call should be for three months; and to further conform to the provisions of the Act of 1795, under which the call was issued, the President's proclamation also convened the Congress in special session on the coming fourth of July.