The most prominent case, however, was that of Colonel Robert E. Lee, the officer who captured John Brown at Harper's Ferry, and who afterward became the leader of the Confederate armies. As a lieutenant he had served on the staff of General Scott in the war with Mexico. Personally knowing his ability, Scott recommended him to Lincoln as the most suitable officer to command the Union army about to be assembled under the President's call for seventy-five regiments; and this command was informally tendered him through a friend. Lee, however, declined the offer, explaining that "though opposed to secession, and deprecating war, I could take no part in an invasion of the Southern States." He resigned his commission in a letter written on April 20, and, without waiting for notice of its acceptance, which alone could discharge him from his military obligation, proceeded to Richmond, where he was formally and publicly invested with the command of the Virginia military and naval forces on April 22; while, two days later, the rebel Vice-President, Alexander H. Stephens, and a committee of the Richmond convention signed a formal military league making Virginia an immediate member of the Confederate States, and placing her armies under the command of Jefferson Davis. The sudden uprising in Maryland and the insurrectionary activity in Virginia had been largely stimulated by the dream of the leading conspirators that their new confederacy would combine all the slave States, and that by the adhesion of both Maryland and Virginia they would fall heir to a ready-made seat of government. While the bombardment of Sumter was in progress, the rebel Secretary of War, announcing the news in a jubilant speech at Montgomery, in the presence of Jefferson Davis and his colleagues, confidently predicted that the rebel flag would before the end of May "float over the dome of the Capitol at Washington." The disloyal demonstrations in Maryland and Virginia rendered such a hope so plausible that Jefferson Davis telegraphed to Governor Letcher at Richmond that he was preparing to send him thirteen regiments, and added: "Sustain Baltimore if practicable. We reinforce you"; while Senator Mason hurried to that city personally to furnish advice and military assistance.