The plan at first sight seemed promising.  But in Lincoln’s eyes it had this great defect:  during the time McClellan was moving round by water and disembarking his troops—­and this, so few were the transports, would take at least a month—­Johnston might make a dash at Washington.  The city had been fortified.  A cordon of detached forts surrounded it on a circumference of thirty miles.  The Potomac formed an additional protection.  But a cordon of isolated earthworks does not appeal as an effective barrier to the civilian mind, and above Point of Rocks the great river was easy of passage.  Even if Washington were absolutely safe from a coup de main, Lincoln had still good reason for apprehension.  The Union capital was merely the seat of government.  It had no commercial interests.  With a population of but 20,000, it was of no more practical importance than Windsor or Versailles.  Compared with New York, Pittsburg, or Philadelphia, it was little more than a village.  But, in the regard of the Northern people, Washington was the centre of the Union, the keystone of the national existence.  The Capitol, the White House, the Treasury, were symbols as sacred to the States as the colours to a regiment.* (* For an interesting exposition of the views of the soldiers at Washington, see evidence of General Hitchcock, U.S.A., acting as Military Adviser to the President, O.R. volume 12 part 1 page 221.) If the nation was set upon the fall of Richmond, it was at least as solicitous for the security of its own chief city, and an administration that permitted that security to be endangered would have been compelled to bow to the popular clamour.  The extraordinary taxation demanded by the war already pressed heavily on the people.  Stocks were falling rapidly, and the financial situation was almost critical.  It is probable, too, that a blow at Washington would have done more than destroy all confidence in the Government.  England and France were chafing under the effects of the blockade.  The marts of Europe were hungry for cotton.  There was much sympathy beyond seas with the seceded States; and, should Washington fall, the South, in all likelihood, would be recognised as an independent nation.  Even if the Great Powers were to refuse her active aid in the shape of fleets and armies, she would at least have access to the money markets of the world; and it was possible that neither England nor France would endure the closing of her ports.  With the breaking of the blockade, money, munitions, and perhaps recruits, would be poured into the Confederacy, and the difficulty of reconquest would be trebled.  The dread of foreign interference was, therefore, very real; and Lincoln, foreseeing the panic that would shake the nation should a Confederate army cross the Potomac at Harper’s Ferry or Point of Rocks, was quite justified in insisting on the security of Washington being placed beyond a doubt.  He knew, as also did Jackson, that even a mere demonstration against so vital a point might have the most deplorable effect.  Whatever line of invasion, he asked, might be adopted, let it be one that would cover Washington.