Elements of Military Art and Science Or, Course Of Instruction In Strategy, Fortification, Tactics Of Battles, &C.; Embracing The Duties Of Staff, Infantry, Cavalry, Artillery, And Engineers; Adapted online

defining these terms and explaining their meaning and application, it is
deemed best to illustrate their use by reference to well-known and
striking historical examples.

_The theatre of a war_ embraces not only the territory of the two
belligerent powers, but also that of their allies, and of such secondary
powers as, through fear or interest, may be drawn into the contest. With
maritime nations it also embraces the seas, and sometimes crosses to
another continent. Some of the wars between France and England embraced
the two hemispheres.

_The theatre of operations_, however, is of a more limited character,
and should not be confounded with the theatre of war. In general, it
includes only the territory which an army seeks, on the one hand, to
defend, and on the other, to invade. If two or more armies be directed
towards the same object, though by different lines, their combined
operations are included in the same theatre but if each acts
independently of the others, and seeks distinct and separate objects,
each must have its own independent theatre of operations.

A war between France and Austria may embrace all Italy and Germany, but
the theatre of operations may be limited to only a portion of these
countries. Should the Oregon question lead to hostilities between the
United States and England, the theatre of war would embrace the greater
part of North America and the two oceans, but the theatre of operations
would probably be limited to Canada and our northern frontier, with
naval descents upon our maritime cities.

The first point to be attended to in a plan of military operation is to
select a good _base_. Many circumstances influence this selection, such
as mountains, rivers, roads, forests, cities, fortifications, military
dépôts, means of subsistence, &c. If the frontier of a state contain
strong natural or artificial barriers, it may serve not only as a good
base for offensive operations, but also as an excellent line of defence
against invasion. A single frontier line may, however, be penetrated by
the enemy, and in that case a second or third base further in the
interior becomes indispensable for a good defence.

A French army carrying on military operations against Germany would make
the Rhine its first base; but if driven from this it would form a second
base on the Meuse or Moselle, a third on the Seine, and a fourth on the
Loire; or, when driven from the first base, it would take others
perpendicular to the front of defence, either to the right, on Béfort
and Besançon, or to the left, on Mézières and Sedan. If acting
offensively against Prussia and Russia, the Rhine and the Main would
form the first base the Elbe and the Oder the second, the Vistula the
third, the Nieman the fourth, and the Dwina and the Dnieper the fifth.

A French army operating against Spain would have the Pyrenees for its
first base; the line of the Ebro for a second, resting its wings on the
gulf of Gascony and the Mediterranean. If from this position it advance
its left, possessing itself of the kingdom of Valencia, the line of the
Sierra d'Estellas becomes its third base of operations against the
centre of Spain.

A base may be parallel, oblique, or perpendicular to our line of
operations, or to the enemy's line of defence. Some prefer one plan and
some another; the best authorities, however, think the oblique or
perpendicular more advantageous than the parallel; but we are not often
at liberty to choose between these, for other considerations usually
determine the selection.

In 1806, the French forces first moved perpendicular to their base on
the Main, but afterwards effected a change of front, and moved on a line
oblique or nearly parallel to this base. They had pursued the same plan
of operations in the Seven Years' War. The Russians, in 1812, based
perpendicularly on the Oka and the Kalouga, and extended their flank
march on Wiozma and Krasnoi; in 1813, the allies, based perpendicularly
on Bohemia, succeeded in paralyzing Napoleon's army on the Elbe.

An American army moving by Lake Champlain, would be based perpendicular
on the great line of communication between Boston and Buffalo; if moving
from the New England states on Quebec and Montreal, the line of
operations would be oblique; and if moving from the Niagara frontier by
Lake Ontario and the St. Lawrence, the line would be nearly parallel
both to our base and to the enemy's line of defence - an operation, under
the circumstances, exceedingly objectionable.

Any point in the theatre of operations which gives to the possessor an
advantage over his opponent, is regarded as _strategic_. Their
geographical position and political and military character, give them a
greater or less influence in directing the campaign. These points are
occupied by the defensive army, and attacked by the offensive; if on or
near the base, they become the _key_ points for the former, and the
_objective_ points for the latter.[3] There are also between these two a
greater or less number of strategic points, which have an important
though inferior influence upon the result of the war.

[Footnote 3: It may be well to remark that a strategic point is not
necessarily a geometrical point; an entire province, or a considerable
portion of a geographical frontier, is, in military language, sometimes
denominated a _point_. In the same way, strategic lines, instead of
being mathematical lines, are frequently many miles in width.]

The first object of the French in attacking Belgium, is to gain
possession of the Meuse, as this position would give them a decided
advantage in any ulterior operations. In attacking southern Germany, the
course of the Danube offers a series of points which exercise an
important influence on the war. For northern Germany, Leipsic and the
country bordering on the Saale and the Elbe, are objects often fiercely
contested by the French and other belligerent powers. In a war between
this country and England, Montreal and the points on the St. Lawrence
between Montreal and Quebec, would become objects of the highest
importance, and their possession would probably determine the result of
the war.

The capital of a state, from its political importance as well as its
military influence, is almost always a decisive strategic point, and its
capture is therefore frequently the object of an entire campaign. The
possession of Genoa, Turin, Alexandria, Milan, &c., in 1796, both from
their political and military importance, had a decided influence upon
the results of the war in these several states. In the same way Venice,
Rome, and Naples, in 1797, Vienna, in the campaigns of 1805 and 1809,
Berlin, in 1806, Madrid, in 1808, and Paris, in 1814 and 1815. If
Hannibal had captured the capital immediately after the battle of
Cannae;, 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 _a_ B; and of
course A continues to cover the point _a_ so long as it remains within
this circle _a_ B.

_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 manoeuvred 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, with an army of only one hundred and
twenty thousand men against an allied force of two hundred and twenty
thousand, by his central advance on Charleroi and Ligny, he gained a
most decided advantage over the enemy - an advantage lost by the
eccentric movement of Grouchy: and even in 1813, his central position at
Dresden would have secured him most decisive advantages, had not the
faults of his lieutenants lost these advantages in the disasters of Kulm
and the Katzbach.

For the same frontier it is objectionable to form more than one army;
grand detachments and corps of observation may frequently be used with
advantage, but double or multiple lines of operation are far less
favorable than one simple line. It may however sometimes occur that the
position of the enemy's forces will be such as to make this operation
the preferable one. In that case, interior lines should always be
adopted, unless we have a vast superiority in number. Double exterior
lines, with corps several days' march asunder, must be fatal, if the
enemy, whether acting on single or double interior lines, take advantage
of his position to concentrate his masses successively against our
isolated forces. The Roman armies under the consuls Flaminius and
Servilius opposed Hannibal on exterior lines, the one by Florence and
Arrezzio, and the other by Modena and Ariminum. Hannibal turned the
position of Flaminius and attacked the Roman armies separately, gaining
a complete and decisive victory. Such also was the character of the
operations of the French in 1795, under Pichegru and Jourdan; they met
with a bloody and decisive defeat. Again in 1796, the French armies
under Jourdan and Moreau, pursued exterior lines; the Archduke Charles,
from his interior position, succeeded in defeating both the opposing
generals, and forcing them to retreat. If the two armies united had
pursued a single line, the republican flag had been carried in triumph
to Vienna.

_Converging_ lines of operation are preferable, under most
circumstances, to diverging lines. Care should be taken, however, that
the point of meeting be such that it may not be taken as a strategic
position by the enemy, and our own forces be destroyed in detail, before
they can effect a junction. In 1797 the main body of the Austrians,
under Alvinzi, advanced against Napoleon, on three separate lines,
intending to concentrate at Rivoli, and then attack the French in mass;
but Napoleon took his strategic position at Rivoli, and overthrew the
enemy's corps as they successively appeared. In the same way the
Archduke Charles took an interior position, between Moreau and Jourdan,
in 1796, and prevented them from concentrating their forces on a single
point. Wurmser and Quasdanowich attempted to concentrate their forces on
the Mincio, by moving on the opposite shores of Lake Garda; but Napoleon
took an interior position and destroyed them. In 1815 Blucher and
Wellington, from their interior position, prevented the junction of
Napoleon and Grouchy.

_Diverging_ lines may be employed with advantage against an enemy
immediately after a successful battle or strategic manoeuvre; for by
this means we separate the enemy's forces, and disperse them; and if
occasion should require it, may again concentrate our forces by
converging lines. Such was the manoeuvre of Frederick the Great, in
1757, which produced the battles of Rosbach and Leuthen; such also was
the manoeuvre of Napoleon at Donawert in 1805, at Jena in 1806, and at
Ratisbon in 1809.

_Interior_ lines of operations, when properly conducted, have almost
invariably led to success: indeed every instance of failure may be
clearly traced to great unskilfulness in their execution, or to other
extraneous circumstances of the campaign. There may, however, be cases
where it will be preferable to direct our forces on the enemy's flank;
the geographical character of the theatre of war, the position of other
collateral forces, &c., rendering such a direction necessary. But as a
general rule, interior and central lines, for an army of moderate
forces, will lead to decisive results.

Napoleon's Italian campaigns in 1796 and 1797, the campaign of the
Archduke Charles in 1796, Napoleon's campaigns of 1805 and 1809 against
Austria, and of 1806 and 1807 against Prussia and Russia, of 1808 in
Spain, his manoeuvres in 1814, between the battle of Brienne and that
of Paris, and his operations previous to the Battle of Ligny in 1815,
are all brilliant examples under this head.

To change the line of operations, in the middle of a campaign, and
follow _accidental lines_, is always a delicate affair, and can only be
resorted to by a general of great skill, and with disciplined troops. In
such a case it may be attended with important results. It was one of
Napoleon's maxims, that "a line of operations, when once chosen, should
never be abandoned." This maxim, however, must sometimes be disregarded
by an army of undisciplined troops, in order to avoid entire
destruction; but the total abandonment of a line of operations is always
attended with great loss, and should be regarded as a mere choice of
evils. A regular army can always avoid this result, by changing the
direction of its line; thus frequently gaining superior advantages in
the new theatre of action. If the plan of this change be the result of a
good _coup d'oeil_, and it be skilfully executed, the rear of the
operating army will be secure from the enemy; and moreover, he will be
left in doubt respecting its weak points. But such is the uncertainty of
this manoeuvre, that it is very rarely taken by the best troops, unless
actually forced upon them. If the army be of incongruous materials,
generally a change of direction will be less advantageous than to
entirely abandon the line, and save as many as possible of the troops
for some new plan of operations. (Maxim 20.) If, however, the
undisciplined army be sustained by fortifications, it can take up the
_accidental line of operations_ in the same manner, and with the same
probability of success, as is done by a regular force.

We have examples of accidental lines in the operations of the king of
Prussia, after the battle of Hohenkirchen, and of Washington, in
New-Jersey, after the action of Princeton. This is one of the finest in
military history. Napoleon had projected a change in his line of
operations, in case he lost the battle of Austerlitz; but victory
rendered its execution unnecessary. Again in 1814 he had planned an
entire change of operations; but the want of co-operation of the forces
under Mortier and Marmont forced him to abandon a plan which, if
properly executed, had probably defeated the allies. Jomini pronounced
it one of the most brilliant of his military career.

Having explained the principal terms used in strategy, let us trace out
the successive operations of war in their usual strategic relations.

We will suppose war to be declared, and the army to be just entering
upon a campaign. The political and military authorities of the state
determine upon the nature of the war, and select the theatre of its
enterprises. The chief selects certain points, on or near the borders of
the seat of war, where his troops are to be assembled, and his
_materiel_ collected. These points, together, form his base of
operations. He now selects some point, within the theatre of the war, as
the first object of his enterprises, and chooses the line of operations
most advantageous for reaching this objective point. The temporary
positions taken on this line become strategic positions, and the line in
his rear, a line of defence. When he arrives in the vicinity of his
first object, and the enemy begins to oppose his enterprises, he must
force this enemy to retreat, either by an attack or by manoeuvres. For
this purpose he temporarily adopts certain lines of manoeuvre, which may
deviate from his general line of operations. The ulterior events of the
campaign may possibly cause him to make these new, or accidental lines,
his lines of operations. The approach of hostile forces may cause him to
detach secondary corps on secondary lines; or to divide his army, and
pursue double or multiple lines. The primitive object may also be
relinquished, and new ones proposed, with new lines and new plans of
operations. As he advances far from his primitive base, he forms new
depots and lines of magazines. He may encounter natural and artificial
obstacles. To cross large rivers in the face of an enemy is a hazardous
operation; and he requires all the art of the engineer in constructing
bridges, and securing a safe passage for his army. If a fortified place
is to be taken, he will detach a siege corps, and either continue his
march with the main army, or take a strategic position to cover this
siege. Thus Napoleon, in 1796, with an army of only 50,000 combatants,
could not venture to penetrate into Austria, with Mantua and its
garrison of 25,000 men in his rear, and an Austrian force of 40,000
before him. But in 1806 the great superiority of his army enabled him to
detach forces to besiege the principal fortresses of Silesia, and still
to continue his operations with his principal forces. The chief of the
army may meet the enemy under circumstances such as to induce or compel
him to give battle. If he should be victorious, the enemy must be