We have seen that it was one of Napoleon’s maxims that an army should choose the shortest and most direct line of operations, which should either pierce the enemy’s line of defence, or cut off his communications with his base.  It is the opinion of men of the best military talent in our army that the Lake Champlain line satisfies all these conditions at the same time;—­that it is the most direct, most feasible, and most decisive line which can be pursued in case of operations against Canada; and that it is indispensable to success in war that this line be well fortified in time of peace.  All agree that the St. Lawrence above Quebec constitutes the key point of the enemy’s defence, and the objective point towards which all our operations should be directed.  To reach this point, all our Boards of Engineers have deemed it best to collect our troops at Albany and advance by Lake Champlain, a distance of only two hundred miles.  Besides the advantages of a good water communication the whole distance for the transportation of military stores, there are several roads on each side, all concentrating on this line within our own territory.  It has already been shown by the brief sketch of our northern wars, that this line has been the field of strife and blood for fifteen campaigns.  Nature has marked it out as our shortest and easiest line of intercourse with Canada, both in peace and war.  Military diversions will always be made on the eastern and western extremities of this frontier, and important secondary or auxiliary operations be carried on by the eastern and western routes; but until we overthrow the whole system of military science as established by the Romans, revived by Frederick and practised and improved by Napoleon, the central and interior line, under all ordinary circumstances, will furnish the greatest probabilities of success.

If the line of Lake Champlain is, as we have endeavored to show, the most important line in the north; its security by fortifications is a matter of the greatest interest.  The works recommended by the Board, consist of a single fort, costing $600,000, at Rouse’s Point, on the extreme frontier, and unfortified depots at Plattsburg and Albany.  But is this sufficient to accomplish the object?  If the hostile army should pass the extreme frontier barrier, what is to retard his advance,—­what defensive works are to protect the debouche of the Northern canal, or even to save the great central depot?  We know of no foreign engineer who has recommended less than three lines of fortifications for the security of a land frontier; and Napoleon, the Archduke Charles, and General Jomini, agree in recommending at least this number of lines.  There may be circumstances that render it unnecessary to resort to a three-fold defence throughout the whole extent of our northern frontier; but upon our main line of communication with Canada,—­a line of maximum importance both to us and to the enemy, we know of no reason for violating the positive rules of the art,—­rules which have been established for ages; and sanctioned by the best engineers and greatest generals of modern times.