Elements of Military Art and Science. H. W. Halleck
of Cannæ;, he would thus have destroyed the Roman power. The taking of Washington, in 1814, had little or no influence on the war, for the place was then of no importance in itself, and was a mere nominal capital. It, however, greatly influenced our reputation abroad, and required many brilliant successes to wash the blot from our national escutcheon.
Lines of defence in strategy are either permanent or temporary. The great military frontiers of a state, especially when strengthened by natural and artificial obstacles, such as chains of mountains, rivers, lines of fortresses, &c., are regarded as permanent lines of defence. The Alpine range between France and Piedmont, with its fortified passes; the Rhine, the Oder, and the Elbe, with their strongly-fortified places; the Pyrenees, with Bayonne at one extremity and Perpignon at the other; the triple range of fortresses on the Belgian frontier—are all permanent lines of defence. The St. Lawrence river is a permanent line of defence for Canada; and the line of lake Champlain, the upper St. Lawrence, and the lakes, for the United States.
Temporary lines of defence are such as are taken up merely for the campaign. Napoleon's position in Saxony, in 1813; the line of the allies in Belgium, in 1815; the line of the Marne, in 1814, are examples of temporary lines of defence.
It will be seen from these remarks that lines of defence are not necessarily bases of operation.
Strategic positions are such as are taken up during the operations of a war, either by a corps d'armée or grand detachment, for the purpose of checking or observing an opposing force; they are named thus to distinguish them from tactical positions or fields of battle. The positions of Napoleon at Rivoli, Verona, and Legnano, in 1796 and 1797, to watch the Adige; his positions on the Passarge, in 1807, and in Saxony and Silesia in front of his line of defence, in 1813; and Massena's positions on the Albis, along the Limmat and the Aar, in 1799, are examples under this head.
Before proceeding further it may be well to illustrate the strategic relations of lines and positions by the use of diagrams.
(Fig. 1.) The army at A covers the whole of the ground in rear of the line DC perpendicular to the line AB, the position of the enemy being at B.
(Fig. 2.) AJ being equal to BJ, A will still cover every thing in rear of DC.
(Fig. 3.) If the army A is obliged to cover the point a, the army B will cover all the space without the circle whose radius is aB; and of course A continues to cover the point a so long as it remains within this circle aB.
A line of operations embraces that portion of the theatre of war which an army or corps d'armée passes over in attaining its object; the front of operations is the front formed by the army as it advances on this line.
When an army acts as a single mass, without forming independent corps, the line it follows is denominated a simple line of operations.
If two or more corps act in an isolated manner, but against the same opposing force, they are said to follow double or multiple lines.
The lines by which Moreau and Jourdan entered Germany in 1796, were double lines; but Napoleon's advance by Bamberg and Gera, in 1806, although moving in seven distinct corps d'armée, formed but a single line of operations.
Interior lines of operations are those followed by an army which operates between the enemy's lines in such a way as to be able to concentrate his forces on one of these lines before the other can be brought to its assistance. For example, Napoleon's line of operations in 1814, between the Marne and the Seine, where he manœuvred with so much skill and success against the immensely superior forces of the allies.
Exterior lines present the opposite results; they are those which an army will form in moving on the extremities of the opposing masses. For example, the lines of the Marne and the Seine, followed by the army of Silesia and the grand Austro-Russian army, in the campaign of 1814. Burgoyne's line of operations, in 1777, was double and exterior.
Concentric lines are such as start from distant points, and are directed towards the same object, either in the rear or in advance of their base.
If a mass leaves a single point and separates into several distinct corps, taking divergent directions, it is said to pursue eccentric lines.
Lines are said to be deep, when the end to be attained is very distant from the base.
The lines followed by a secondary or auxiliary force are denominated secondary lines.
The lines pursued by the army of the Sombre-et-Meuse in 1796, and by Bagration in 1812, were secondary lines, as the former were merely secondary to the army of the Rhine, and the latter to that of Barclay.
Accidental lines are those which result from a change in the primitive plan of campaign, which give a new direction to the operations. These are of rare occurrence, but they sometimes lead to important results.
The direction given to a line of operations depends not only on the geographical situation of the country, but also on the positions occupied by the enemy. The general plan of campaign is frequently determined on previous to beginning operations, but the choice of lines and positions must ordinarily result from the ulterior events of the war, and be made by the general as these events occur.
As a general rule, a line of operations should be directed upon the centre, or one of the extremities of the enemy's line of defence; unless our forces be infinitely superior in number, it would be absurd to act against the front and extremities at the same time.
If the configuration of the theatre of operations be favorable to a movement against the extremity of the enemy's line of defence, this direction maybe best calculated to lead to important results. (Fig.4.)
In 1800 the army of the Rhine was directed against the extreme left of the line of the Black Forest; the army of reserve was directed by the St. Bernard and Milan on the extreme right and rear of Melas's line of defence: both operations were most eminently successful. (Fig. 5.)
It may be well to remark that it is not enough merely to gain the extremity and rear of the enemy, for in that case it may be possible for him to throw himself on our communications and place us in the very dilemma in which we had hoped to involve him. To avoid this danger it is necessary to give such a direction to the line of operations that our army shall preserve its communications and be able to reach its base.
Thus, if Napoleon, in 1800, after crossing the Alps, had marched by Turin on Alexandria and received battle at Marengo, without having first secured Lombardy and the left of the Po, his own line of retreat would have been completely cut off by Melas; whereas, by the direction which he gave to his line of operations he had, in case of reverse, every means for reaching either the Var or the Valois. (Fig. 6.) Again, in 1806, if he had marched directly from Gera to Leipsic, he would have been cut off from his base on the Rhine; whereas, by turning from Gera towards Weimar, he not only cut off the Prussians from the Elbe, but at the same time secured to himself the roads of Saalfield, Schleitz, and Hoff, thus rendering perfectly safe his communications in his rear. (Fig. 7.)
We have said that the configuration of the ground and the position of the hostile forces may sometimes render it advisable to direct our line of operations against the extremity of the enemy's line of defence; but, as a general rule a central direction will lead to more important results. This severs the enemy's means of resistance, and enables the assailant to strike, with the mass of his force, upon the dissevered and partially paralyzed members of the hostile body. (Fig. 8.)
Such a plan of operations enabled Napoleon, in the Italian campaigns of 1796 and 1797, to pierce and destroy, with a small force, the large and successive armies which Austria sent against him. In 1805 his operations were both interior and central: in 1808 they were most eminently central: in 1809, by the central operations in the vicinity of Ratisbonne, he defeated the large and almost victorious army of the Archduke Charles: in 1814, from his central position between the Marne and Seine, with only seventy thousand men against a force of more than two hundred thousand, he gained numerous victories, and barely failed of complete success. Again in 1815,