The Call for Troops was made, as we have seen, on the 15th day of April. On the evening of the following day several companies of a Pennsylvania Regiment reported for duty in Washington. On the 18th, more Pennsylvania Volunteers, including a company of Artillery, arrived there. On the 19th of April, the Sixth Massachusetts Regiment--whose progress through New York city had been triumphal-was suddenly and unexpectedly assailed, in its passage through Baltimore, to the defense of the National Capital, by a howling mob of Maryland Secessionists--worked up to a pitch of States-rights frenzy by Confederate emissaries and influential Baltimore Secession-sympathizers, by news of the sudden evacuation of the Federal Arsenal at Harper's Ferry, and other exciting tidings--and had to fight its way through, leaving three soldiers of that regiment dead, and a number wounded, behind it. [At a meeting of the "National Volunteer Association," at Monument Square, Baltimore, the previous evening, says Greeley's History of the American Conflict, page 462, "None of the speakers directly advocated attacks on the Northern troops about to pass through the city; but each was open in his hostility to 'Coercion,' and ardently exhorted his hearers to organize, arm and drill, for the Conflict now inevitable. Carr (Wilson C. N. Carr) said: 'I do not care how many Federal troops are sent to Washington; they will soon find themselves surrounded by such an army from Virginia and Maryland, that escape to their homes will be impossible; and when the 75,000 who are intended to invade the South shall have polluted that soil with their touch, the South will exterminate and sweep them from the Earth.' (Frantic cheering and yelling). The meeting broke up with stentorian cheers for 'the South' and for 'President Davis."'] Ten companies of Philadelphia troops, reaching Baltimore at the same time, unarmed, were also violently assailed by the crazy mob, and, after a two hours' fight, reached the cars and returned to Philadelphia. Washington City--already, by the Secession of Virginia, cut off from the South--was thus practically cut off from the North as well; and to isolate it more completely, the telegraph wires were cut down and the railroad bridges burned. A mere handful of regulars, the few volunteers that had got through before the outbreak in Baltimore, and a small number of Union residents and Government department clerks--these, under General Winfield Scott, constituted the paltry force that, for ten days after the Call for troops, held the National Capital. Informed, as the Rebels must have been, by their swarming spies, of the weakness of the Federal metropolis, it seems absolutely marvelous that instant advantage was not taken of it.