Читать книгу Elements of Military Art and Science - H. W. Halleck - Страница 9
CHAPTER III.
ОглавлениеFORTIFICATIONS.
Fortifications, or engineering, may be considered with reference to the defence of states and the grand operation of armies; or with reference to the details of the construction, and attack, and defence of forts, and the influence of field-works on the tactical manœuvres of armies. It is proposed to speak here only of its general character, as a branch of the military art, without entering into any professional discussion of details.
The connection of fortification and strategy may be considered under two distinct heads: 1st, the choice of sites for constructing fortresses for defence; 2d, their influence in offensive operations, and the determination of the question whether they can be passed with safety, or whether the attacking force will be under the necessity of besieging them.
The centre and extremities of a base of operations should always be secured either by natural or artificial obstacles. This base is generally chosen so that fortifications will be necessary for strengthening only a part of the line. But if a frontier, like the side of France towards Belgium, be destitute of natural obstacles, the artificial means of defence must be proportionally increased. Great care should be taken that permanent fortifications be made only on such places as may favor military operations. If otherwise, the troops detached from the active army for garrisoning them, will only tend to weaken this force without any corresponding advantages. In this way, fortifications may become actually injurious to defence. A number of the European fortresses which were built before the subject of strategy was properly understood, are now regarded as utterly useless, from their ill-advised positions.
Whether a fortress may be safely passed with merely blockading or observing it, depends very much upon the nature of the war, and the numbers and position of the defensive army. The allies, in 1814, invading France with a million of soldiers, assisted by the political diversion of factions and Bourbonists within the kingdom, and treason in the frontier fortresses, and even in the ranks of Napoleon's army, could conduct their military operations on a very different plan from that which would be adopted by either Austria, Prussia, Russia, England, Spain, Portugal, Holland, Italy, and the German powers, if singly waging war with the French. Napoleon sometimes detached a corps to observe a fortress which threatened his line of operations or of manœuvre; at others, he delayed his advance till the place could be reduced.
"An army," says Jomini, "may sometimes penetrate between places on an open frontier, to attack the enemy's forces in the field, taking care at the same time to observe these places; but no invading army can cross a great river, like the Danube, the Rhine, or the Elbe, without reducing at least one of the fortresses on that river, so as to secure a line of retreat; but being in possession of such a place, it can continue the offensive, while its matériel de siège successively reduces the other places."
In case the main army is obliged to remain and cover the besieging corps, it should take some central position, where it can command all the avenues of approach, and fall with vigor on the enemy, should he attempt to raise the siege. Napoleon's operations before Mantua, in 1796, offer the finest model for imitation.
The old system of intrenched camps and lines of contravallation is unsuited to the spirit of modern warfare. In ancient times, and more particularly in the middle ages, too much importance was attached to tactical positions, and not enough to strategic points and lines. This gave to fortifications a character that never properly belonged to them. From the middle ages down to the period of the French Revolution, wars were carried on mainly by the system of positions—one party confining their operations to the security of certain important places, while the other directed their whole attention to the siege and capture of these places. But Carnot and Napoleon changed this system, at the same time with the system of tactics, or rather, returned from it to the old and true system of strategic operations. Some men, looking merely at the fact that a change was made, but without examining the character of that change, have rushed headlong to the conclusion that fortified places are now utterly useless in war, military success depending entirely upon a good system of marches.
On this subject, General Jomini, the great military historian of the wars of the French Revolution, remarks that "we should depend entirely upon neither organized masses, nor upon material obstacles, whether natural or artificial. To follow exclusively either of these systems would be equally absurd. The true science of war consists in choosing a just medium between the two extremes. The wars of Napoleon demonstrated the great truth, that distance can protect no country from invasion, but that a state, to be secure, must have a good system of fortresses, and a good system of military reserves and military institutions."
In all military operations time is of vast importance. If a single division of an army can be retarded for a few hours only, it not unfrequently decides the fate of the campaign. Had the approach of Blucher been delayed for a few hours, Napoleon must have been victorious at the battle of Waterloo. An equilibrium can seldom be sustained for more than six or seven hours between forces on the field of battle; but in this instance, the state of the ground rendered the movements so slow as to prolong the battle for about twelve hours; thus enabling the allies to effect a concentration in time to save Wellington.
Many of Napoleon's brilliant victories resulted from merely bringing troops to bear suddenly upon some decisive point. Rivoli in 1796–7, Marengo in 1800, Ulm in 1805, Jena in 1806, Ratisbon in 1809, Brienne in 1814, and Ligny in 1815, are familiar examples. But this concentration of forces, even with a regular army, cannot be calculated on by the general with any degree of certainty, unless his communications are perfectly secure. And this difficulty is very much increased where the troops are new and undisciplined. When a country like ours is invaded, large numbers of such troops must suddenly be called into the field. Not knowing the designs of the invaders, much time will be lost in marches and countermarches; and if there be no safe places of resort the operations must be indecisive and insecure.
To a defensive army fortifications are valuable as points of repose, upon which the troops, if beaten, may fall back, and shelter their sick and wounded, collect their scattered forces, repair their materials, and draw together a new supply of stores and provisions; and as rallying points, where new troops may be assembled with safety, and the army, in a few days, be prepared to again meet the enemy in the open field. Without these defences, undisciplined and inexperienced armies, when once routed, can seldom be rallied again, except with great losses. But when supported by forts, they can select their opportunity for fighting, and offer or refuse battle according to the probability of success; and, having a safe place of retreat, they are far less influenced by fear in the actual conflict.
The enemy, on the other hand, being compelled either to besiege or observe these works, his army will be separated from its magazines, its strength and efficiency diminished by detachments, and his whole force exposed to the horrors of partisan warfare. It has therefore been estimated by the best military writers, that an army supported by a judicious system of fortifications, can repel a land force six times as large as itself.
Every government should prepare, in time of peace, its most prominent and durable means of defence. By securing in a permanent manner its important points, it will enable a small force to retain possession of these places against a greatly superior army, for a considerable length of time. This serves the same purpose as a battle gained; for, in the beginning of a war of invasion, the economy of time is of the utmost importance to the defensive party, enabling it to organize and prepare the great military resources of the state.
In all mountainous frontiers, or sides of states bordering on large rivers, or chains of lakes, there will necessarily be but few points by which an invader can penetrate into the interior of the country. Let us suppose that, for a frontier of moderate extent, there are five passes, or avenues through which the enemy may approach the interior. To effectually defend these approaches against the invading army will require, for each, an army of ten thousand men. Not being able to decide positively on the plans of the enemy, all these communications must be defended at the same time. This requires a defending army of fifty thousand men. Let us now suppose each of these passes to be fortified in such a way, that one thousand men will be able to hold the enemy in check, and force him to resort to the operations of a siege; or, at least, to retard his advance till an active army can be organized in the interior, and prepared to meet him in the field. We here see that five thousand men, by means of fortifications, can accomplish the same defensive object as fifty thousand men without these artificial means of security.
But let us enter a little more into the details of frontier defences, and examine the character of the several systems which have been successively proposed or adopted. Frontiers are divided into four distinct classes, according as the state may be open on one or more sides, or bounded by mountains, large rivers and lakes, or by the sea.
An open frontier is the most difficult of defence; and while there exists a perfect uniformity among military men upon the vast importance of fortifying such a frontier, there is an equal diversity of opinion respecting the best manner of arranging these works. We shall here mention three general systems of arranging forts for the defence of an open country, each of which has been advocated at different times, and afterwards received various modifications and additions. These three systems comprise the main features of all others worthy of much consideration. They are:—
1st. The system of continuous lines, proposed by Montalembert.
2d. A system of three lines of detached works, strongly recommended by D'Arçon and others.
3d. A system proposed by Vauban, and advocated by Rogniat, consisting of lines of very strong works, placed at considerable distances from each other and covering large intrenched camps.
The first of these systems was proposed in 1790, and for a time attracted considerable notice in France, but has long since been discarded, as being utterly incompatible with the principles of the military art. A writer, however, of some pretensions in this country, recommends its adoption for the defence of Baltimore and the shores of the Chesapeake. The same author would dispense entirely with our present system of fortifications on the sea-coast, and substitute in their place wooden Martello towers! This would be very much like building 120 gun ships at Pittsburg and Memphis, for the defence of the Ohio and the Mississippi rivers, and sending out duck-boats to meet the enemy on the Atlantic!
In the second system, the works on the extreme frontier are to be placed about thirty or forty miles apart, and those of the second and third lines respectively thirty or forty miles in rear of the first and second lines, and opposite the intervals.
In the third system, first recommended by Vauban and more recently by Rogniat, the works are to be arranged in the same manner as in that of D'Arçon, but the distance between them is to be from seventy to one hundred miles, and each fort arranged for covering a large intrenched camp.
Either of these last two systems is well suited to the defence of an open frontier. The former is applied to the side of France towards Belgium, and the latter, with certain modifications, to the defence of Western Germany. The first line of fortifications on the northern frontier of France consists of Dunkirk, Lille, Valenciennes, Condé, Quesnoy, Rocroi, Charlemont, Mézières, and Sedan; the second line, of Calais, Andres, St. Omer, Béthune, Arras, Douai, Chambrai, Landrecies, and Avesnes; the third line, of Boulogne, Montreuil, Hesdin, Abbeville, Amiens, Bapaume, Peronne, Ham, and Laon.
For mountainous frontiers it is deemed necessary to secure all the important passes with small redoubts or military works, and to defend with strong forts the grand interior strategic points on which these communications are directed. For a frontier of moderate extent there may be some six or eight gorges in the mountains by which an army might penetrate; but it will always be found that these roads concentrate on two or three points in the great valleys below. Take, for example, the frontier of France towards Switzerland and Italy. The passes of the mountains are secured by the little works of Fort L'Ecluse, Fort Pierre-châtel, Fort Barraux, Briançon, Mont Dauphin, Colmars, Entrevaux, and Antibes; while Besançon, Grenoble, and Toulon, form a second line; and Lyons a grand central dépôt.
Where a great river or chain of lakes forms the boundary of a state, the system of defence will be much the same as that of an open land frontier, the works of the first line being made to secure the great bridges or ferries by which the enemy might effect a passage; those of the second line, to cover the passes of the highlands that generally approach more or less near the great watercourse; and those of the third line, far enough in rear to protect the great internal communications of the country. Let us take, for example, the side of France bordering on the Rhine. Wissembourg and Lauterbourg, Fort Louis, Haguenau, Strasbourg, Schelstadt, Neuf-Brisach, and Huneguen, cover the several passages of the river; while Bitche, Phalsbourg, and Béfort form a second line; Thionville, Metz, and Toul, a third line; and Verdun a grand central dépôt.
The following are the principal objects proposed to be accomplished by fortifications on a sea-coast.
1st. To close all important harbors to an enemy, and secure them to the navy of the country.
2d. To prevent the enemy from forming an establishment on our shores, from which, by his naval superiority, he might destroy our commerce and keep the whole frontier in continual alarm.
3d. To cover our great cities against a maritime attack and bombardment.
4th. To cover our ship-yards and great naval dépôts.
5th. To prevent, as much as possible, the great avenues of interior navigation from being blockaded by naval means at their entrance into the ocean.
6th. To give to our navy facilities for protecting our coast trade from the enemy's ships of war, and our internal communications, which lie near the coast, from maritime descents.
Let us notice how France has attempted to accomplish this object. The Mediterranean frontier has Fort Quarré, Fort St. Marguérite, St. Tropez, Brigançon, the forts of Point Man, of l'Ertissac, and of Langoustier, Toulon, St. Nicholas, Castle of If, Marseilles, Tour de Boue, Aigues-Montes, Fort St. Louis, Fort Brescou, Narbonne, Château de Salces, Perpignan, Collioure, Fort St. Elme, and Port Vendre. Toulon is the great naval dépôt for this frontier, and Marseilles the great commercial port. Both are well secured by strong fortifications. The Atlantic frontier has Bayonne; the forts of Royan, Grave, Medoc, Paté, &c., on the Gironde; Rochefort, with the forts of Chapus, Lapin, Aix, Oleron, &c., to cover the roadstead; La Rochelle, with the forts of the Isle of Ré; Sables, with the forts of St. Nicholas, and Des Moulines, Isle Dieu, Belle Isle, Fort du Pilier, Mindin, Ville Martin; Quiberon, with Fort Penthièvre; L'Orient, with its harbor defences; Fort Cigogne; Brest, with its harbor defences; St. Malo, with Forts Cézembre, La Canchée, L'Anse du Verger, and Des Rimains; Cherbourg, with its defensive forts and batteries; Havre, Dieppe, Boulogne, Calais, and Dunkirk. Cherbourg, Brest, and Rochefort, are great naval dépôts; and Havre, Nantes, and Bordeaux, the principal commercial ports. Many of the works above enumerated are small in extent and antiquated in their construction, and some of them quite old and dilapidated nevertheless, they have heretofore been found sufficient for the defence of the naval dépôts and commercial seaports of France against the superior naval forces of her neighbor.
Omitting for the present all discussion of sea-coast defences, let us examine more particularly the character and influence of fortifications on land frontiers.
All military writers agree that fortifications have heretofore exerted a great, and frequently a decisive, influence on the operations of a war. Those of France are frequently referred to as proofs of this influence. But, while all are disposed to allow that these works contributed much in former times to the defence of states, yet some have said that modern improvements in the mode of attack have rendered forts far less valuable than formerly.
Such, however, is not the case. Improvements in the mode of attack have not kept pace with the facilities of locomotion; and, although fortifications do not now usually sustain a siege of as many days as in former times, still, as compared with the relative lengths of campaigns in ancient and modern wars, the proportional length of sieges is now even greater than formerly. When the same is accomplished in a campaign of seven weeks as was formerly done in a war of seven years, it is not necessary that fortified places should hold out a very long time. A place that can sustain a siege of a month is now deemed sufficiently strong for ordinary campaigns; for by the end of that time the defensive army will either be destroyed, or be able to come to its succor. In either case a longer defence would not be required.
A reference to the most important sieges of the last century or two will show that forts are, on an average, capable of sustaining a siege for more than that length of time. Lille, in 1708, held the allies in check for a whole year; and again, in 1792, compelled the Austrians to raise the siege after an unsuccessful attack of fifteen days.
Antwerp, in 1585, sustained a siege of fourteen months against greatly superior forces; in 1814 Carnot defended the citadel of this place for four months, and until an armistice had been concluded between the contending parties; in 1832, it sustained, with a garrison of only 4,500 men and 145 pieces of ordnance, a siege of twenty-five days, against a force of 55,000 men and 223 cannon.
Namur, near the end of the seventeenth century, sustained a siege of ten weeks.
Ismaïl, in 1790, sustained a siege of more than two months against the Russians.
Maestricht, in 1793, sustained a siege of nearly two weeks; and again, in 1794, sustained a blockade and siege of nearly two months.
Magdeburg, in the thirty years' war, resisted the army of Wallenstein for seven months; and in 1813–14, although garrisoned by only 4,000 men, it for a long time resisted the overwhelming forces of the allies.
Dantzic, at the same time, sustained a siege against superior forces for more than nine months.
Landau, in 1793, sustained a siege of nine months.
Valenciennes and Mayence, in 1793, each sustained a siege of about three months.
Charleroi, Fort Vauban, and L'Ecluse, in 1794, each sustained a siege of about thirty days.
Quesnoy, in 1794, sustained a siege of about three weeks.
Rosas, in 1795, sustained a siege of some seventy days.
Mantua, in 1796–7, protected from invasion, for eight months, the Tyrol and the heart of the Austrian monarchy.
Kehl and Huninguen, in 1796, sheltered Moreau for three months against all the efforts of the Archduke Charles.
St. Jean d'Acre, in 1799, sustained a siege of sixty days of open trench.
Ulm, in 1800, held Moreau in check for more than a month.
Genoa, in 1800, sustained a blockade of sixty and a siege of forty days.
Saragossa in 1808 sustained a close siege of near two months; and in 1809 it was again besieged for two months.
Rosas in 1808 sustained a siege of thirty days.
Gerona in 1809 sustained a siege and blockade of seven months, nearly four of them being of open trench.
Mequinenza (a very small work) in 1810 sustained a siege of more than two weeks.
Astorga in 1810 sustained a siege of thirty days; twenty-four being of open trench.
Lerida in 1810 sustained a siege of thirty days, two weeks being of open trench.
Ciudad Rodrigo in 1810 sustained a siege of two months.
Almeida in 1810 sustained a siege of more than a month.
Tortosa in 1810 sustained a siege of six months.
Tarragona in 1811 sustained a siege of nearly two months.
Badajos in 1811 sustained a siege of more than forty days open trench.
Lerida in 1811 sustained a siege of two weeks open trench.
Saguntum in 1811 sustained a siege of a month.
Valencia in 1811–12 sustained a siege of two months
Ciudad Rodrigo in 1812 sustained a blockade of several months, and a close siege of two weeks.
Badajos in 1812 sustained twenty-one days of open trenches.
Burgos in 1812 sustained thirty-three days of open trenches.
St. Sebastian in 1813 sustained a siege and blockade of nearly three months, with fifty-nine days of open trenches.
Pampeluna in 1813 sustained a siege of more than four months.
Monzon in 1813–14 also sustained a siege of more than four months.
This list might be increased with numerous other examples, to show that even poorly fortified towns are capable of defending themselves, on an average, for more than a month. These examples, be it remembered, are nearly all taken from a period of history since any material improvements have been made in the art of attack. Since the time of Vauban the improvements in attack have not kept pace with the increased means of defence. Moreover, these examples are taken from the sieges of towns defended mainly by old and antiquated works, and entirely incapable of offering the same resistance as detached fortifications, with all the modern improvements.
The value of fortifications, as land defences, is sufficiently proved by showing their general capability of resisting an invader, even for a limited period; thus affording us time and opportunity to provide other means of security. But it must not be inferred that forts besieged en règle will necessarily fall after so many days. Such is far from being the case. The besieged have usually great advantages over the besiegers; and unless the latter are vastly superior in number, or the work is of a very inferior character, or the garrison is destitute of the requisite means and energy to resist an attack, they will not be taken.
Mezieres was not taken in 1520; nor Marseilles in 1524; nor Peronne in 1536; nor Landrecies in 1543; nor Metz in 1552; nor Montauban in 1621; nor Lerida in 1647; nor Maestricht in 1676; nor Vienna in 1529, and again in 1683; nor Turin in 1706; nor Conde in 1744; nor Lille in 1792; nor Landau in 1793; nor Ulm in 1800; nor Saragossa in 1808; nor Burgos in 1812. This list might be extended almost indefinitely with the names of places that could be reduced neither by force nor by starvation.
But, as has already been noticed, some have asserted that fortifications have become of little comparative importance, under the new system of warfare introduced during the wars of the French Revolution. On this subject let us consult the opinions of the best military judges of the present century.
Napoleon says of fortifications, "they are an excellent means of retarding, fettering, enfeebling, and disquieting a conquering foe."
"The possession of strategic points," says the Archduke Charles, "is decisive in military operations; and the most efficacious means should, therefore, be employed to defend points whose preservation is the country's safeguard. This object is accomplished by fortifications, inasmuch as they can resist, for a given time, with a small number of troops, every effort of a much larger force; fortifications should, therefore, be regarded as the basis of a good system of defence." "It should be a maxim of state policy in every country, to fortify, in time of peace, all such points, and to arrange them with great care, so that they can be defended by a small number of troops. For the enemy, knowing the difficulty of getting possession of these works, will look twice before he involves himself in a war." "Establishments which can secure strategic advantages are not the works of a moment; they require time and labor. He who has the direction of the military forces of a state, should, in time of peace, prepare for war." "The proper application or neglect of these principles will decide the safety or the ruin of the state." "Fortifications arrest the enemy in the pursuit of his object, and direct his movements on less important points;—he must either force these fortified lines, or else hazard enterprises upon lines which offer only disadvantages. In fine, a country secured by a system of defences truly strategic, has no cause to fear either the invasion or the yoke of the enemy; for he can advance to the interior of the country only through great trouble and ruinous efforts. Of course, lines of fortifications thus arranged cannot shelter a state against all reverses; but these reverses will not, in this case, be attended by total ruin; for they cannot take from the state the means nor the time for collecting new forces; nor can they ever reduce it to the cruel alternative of submission or destruction."
"Fortifications," says Jomini, "fulfil two objects of capital importance—1st. The protection of the frontiers; and 2d. Assisting the operations of the army in the field." "Every part of the frontiers of a state should be secured by one or two great places of refuge, secondary places, and even small posts for facilitating the active operations of the armies. Cities girt with walls and slight ditches may often be of great utility in the interior of a country, as places of deposit, where stores, magazines, hospitals, &c., may be sheltered from the incursions of the enemy's light troops. These works are more especially valuable where such stores, in order not to weaken the regular army by detachments, are intrusted to the care of raw and militia forces." It is not supposed that any system of fortifications can hermetically close a frontier; "but, although they of themselves can rarely present an absolute obstacle to the advance of the hostile army, yet it is indisputable that they straiten its movements, change the direction of its marches, and force it into detachments; while, on the contrary, they afford all the opposite advantages to the defensive army; they protect its marches, favor its debouches, cover its magazines, its flanks, and its movements, and finally furnish it with a place of refuge in time of need."
These opinions were uttered, be it remembered, long since the period at which modern military quacks date the downfall of fortifications as inland defences, by men, too, who were not engineers, and consequently had no professional predilections in favor of fortifications. The Archduke Charles, as a general, knew no rival but Napoleon, and General Jomini is universally regarded as the first military historian of the age. The truth of their remarks on fortifications is most fully confirmed by the military histories of Germany and France.
For a long period previous to the Thirty Years' War, its strong castles and fortified cities secured the German empire from attacks from abroad, except on its extensive frontier, which was frequently assailed, but no enemy was able to penetrate to the interior till a want of union among its own princes opened its strongholds to the Swedish conqueror; nor then, did the cautious Gustavus Adolphus venture far into its territories till he had obtained possession of all the military works that might endanger his retreat.
Again, in the Seven Years' War, when the French neglected to secure their foothold in Germany, by placing in a state of defence the fortifications that fell into their power, the first defeat rendered their ground untenable, and threw them from the Elbe back upon the Rhine and the Mayne. They afterwards took the precaution to fortify their positions, and to secure their magazines under shelter of strong places, and, consequently, were enabled to maintain themselves in the hostile country till the end of the war, notwithstanding the inefficiency of their generals, the great reverses they sustained in the field, the skill and perseverance of the enemy they were contending with, and the weak and vacillating character of the cabinet that directed them.
But this system of defence was not so carefully maintained in the latter part of the eighteenth century, for at the beginning of the French Revolution, says Jomini, "Germany had too few fortifications; they were generally of a poor character, and improperly located." France, on the contrary, was well fortified: and although without armies, and torn in pieces by domestic factions, (we here use the language of the Archduke,) "she sustained herself against all Europe; and this was because her government, since the reign of Louis XIII., had continually labored to put her frontiers into a defensive condition agreeably to the principles of strategy; starting from such a system for a basis, she subdued every country on the continent that was not thus fortified; and this reason alone will explain how her generals sometimes succeeded in destroying an army, and even an entire state, merely by a strategic success."
This may be illustrated by reference to particular campaigns. In 1792, when the Duke of Brunswick invaded France, she had no armies competent to her defence. Their numbers upon paper were somewhat formidable, it is true, but the license of the Revolution had so loosened the bonds of discipline as to effect an almost complete disorganization. "It seemed, at this period," says the historian, "as if the operations of the French generals were dependent upon the absence of their enemies: the moment they appeared, the operations were precipitately abandoned." But France had on her eastern frontier a triple line of good fortresses, although her miserable soldiery were incapable of properly defending them. The several works of the first and second lines fell, one after another, before the slow operations of a Prussian siege, and the Duke of Brunswick was already advancing upon the third, when Dumourier, with only twenty-five thousand men, threw himself into this line, and by a well-conducted war of positions, placing his raw and unsteady forces behind unassailable intrenchments, succeeded in repelling a disciplined army nearly four times as numerous as his own. Had no other obstacle than the French troops been interposed between Paris and the Prussians, all agree that France must have fallen.
In the campaign, of 1793, the French army in Flanders were beaten in almost every engagement, and their forces reduced to less than one half the number of the allies. The French general turned traitor to his country, and the National Guards deserted their colors and returned to France. The only hope of the Republicans, at this crisis, was Vauban's line of Flemish fortresses. These alone saved France. The strongholds of Lille, Condé, Valenciennes, Quesnoy, Landrecies, &c., held the Austrians in check till the French could raise new forces and reorganize their army. "The important breathing-time which the sieges of these fortresses," says an English historian, "afforded to the French, and the immense advantage which they derived from the new levies which they received, and fresh organization which they acquired during that important period, is a signal proof of the vital importance of fortresses in contributing to national defence. Napoleon has not hesitated to ascribe to the three months thus gained the salvation of France. It is to be constantly recollected that the Republican armies were then totally unable to keep the field; that behind the frontier fortresses there was neither a defensive position, nor a corps to reinforce them; and that if driven from their vicinity, the capital was taken and the war concluded."
In the following year, 1794, when France had completed her vast armaments, and, in her turn, had become the invading power, the enemy had no fortified towns to check the progress of the Republican armies; which, based on strong works of defence, in a few weeks overran Flanders, and drove the allies beyond the Rhine.
In the campaign of 1796, when the army of Moreau had been forced into a precipitate retreat by the admirable strategic operations of the Archduke Charles, the French forces owed their safety to the fortifications on the Rhine. These works arrested the enemy's pursuit and obliged him to resort to the tedious operations of sieges; and the reduction of the French advanced posts alone, Kehl and Huninguen, poorly as they were defended, employed all the resources of the Austrian army, and the skill of their engineers, from early in October till late in February. Kehl was at first assaulted by a force four times as numerous as the garrison; if the enemy had succeeded, he would have cut off Moreau's retreat, and destroyed his army. Fortunately the place was strong enough to resist all assaults; and Moreau, basing himself on the fortresses of Alsace, his right covered by Huninguen, Neuf-Brisach, and Béfort, and his left by the iron barrier of the Netherlands, effectually checked the waves of Austrian success.
Let us now turn to the campaigns of Napoleon. In his first campaign in Italy, 1796, the general was directed "to seize the forts of Savona, compel the senate to furnish him with pecuniary supplies, and to surrender the keys of Gavi, a fortress perched on the rocky height commanding the pass of the Bocchetta." Setting out from Savona, he crossed the mountains at a weak point between the Alps and the Apennines, and succeeded in piercing the enemy's line of defence. The king of Sardinia, jealous of Austrian influence, had refused to permit the Austrian army to garrison his line of fortifications. Napoleon, profiting by his victorious attitude, the mutual jealousy of Austria and Sardinia, and the intrigues of his diplomatists, soon gained possession of these important works. "These Sardinian fortresses," he wrote to the Directory, "at once put the Republicans in possession of the keys of the Peninsula." Basing himself on Coni, Mondovi, Ceva, Gavi, and Alessandria, with Tortosa as his dépôt of magazines, he advanced against Lombardy. Now basing himself on the Adda and Po, with the fortress of Pizzighettone as the dépôt of his magazines, he advanced upon the line of the Adige. Pechiera became his next dépôt, and he now had four fortresses in echelon between him and his first dépôt of magazines; and, after the fall of Mantua, basing himself on the Po, he advanced against the States of the Church, making Ferrara and then Ancona, his places of dépôt.
From the solid basis of the fortresses of Piedmont and Lombardy, "he was enabled to turn his undivided attention to the destruction of the Austrians, and thus commence, with some security, that great career of conquest which he already meditated in the imperial dominions." In this campaign of 1797, after scouring his base, he fortified Palma-Nuova, Osapo, &c., repaired the old fortifications of Klagenfurth, and, as he advanced, established, to use his own words, "a good point d'appui at every five or six marches."
Afterwards, when the Austrians had nearly wrested Italy from the weak grasp of Napoleon's successors, the French saved their army in the fortress of Genoa and behind the line of the Var, which had been fortified with care in 1794–5. Numerous attempts were made to force this line, the advanced post of Fort Montauban being several times assaulted by numerous forces. But the Austrian columns recoiled from its murderous fire of grape and musketry, which swept off great numbers at every discharge. Again the assault was renewed with a vast superiority of numbers, and again "the brave men who headed the column almost perished at the foot of the intrenchment; and, after sustaining a heavy loss, they were compelled to abandon the enterprise."
While the forces on the Var thus stayed the waves of Austrian success, Massena, in the fortifications of Genoa, sustained a blockade of sixty, and a siege of forty days, against an army five times as large as his own; and when forced to yield to the stern demands of famine, he almost dictated to the enemy the terms of the treaty. These two defences held in check the élite of the Austrian forces, while the French reserve crossed the Alps, seized the important points of the country, and cut off the Austrian line of retreat. "But even after the victory of Marengo," says Napoleon, "I did not consider the whole of Italy reconquered, until all the fortified places between me and the Mincio should be occupied by my troops. I gave Melas permission to return to Mantua, on condition of his surrendering all these fortresses."
He now directed Chasseloup de Laubat and his engineers to repair and remodel the fortifications of Verona, Legnano, Pechiera, Mantua, the line of the Adda, Milan, Alessandria,[5] Roco d'Aufo, Genoa, and several smaller works; thus forming a quadruple line of defence against Austrian aggression in Italy. These works were of great service to the French in 1805, enabling Massena with fifty thousand men to hold in check the Archduke Charles with more than ninety thousand, while Napoleon's grand army, starting from the solid base of the Rhine, traversed Germany and seized upon the capital of Austria.
More than twenty millions of money were appropriated for this place alone.
The neglect of the Prussians to place their country in a state of military defence, previous to declaring war against Napoleon in 1806, had a most disastrous influence upon the campaign. Napoleon, on the other hand, occupied and secured all the important military positions which he had captured in the preceding campaign. "The Prussians," said he, "made no preparations for putting into a state of defence the fortifications on their first line, not even those within a few marches of our cantonments. While I was piling up bastion upon bastion at Kehl, Cassel, and Wesel, they did not plant a single palisade at Magdeburg, nor put in battery a single cannon at Spandau." The works on the three great lines of the Oder, the Elbe, and the Weser, had they been properly repaired, garrisoned, and defended, were sufficient to have held in check the French, even after the great victory of Jena, till the newly-organized forces, acting in concert with the Russian army, could re-establish the Prussian monarchy in its ancient greatness. Profiting by the neglect of the Prussians, Napoleon seized upon the great defensive works of the country, which, to his great joy, were readily surrendered into his hands by the old and inefficient generals who commanded them; and French garrisons were almost immediately established in the fortresses of Stettin, Custrin, Glogau, Magdeburg, Spandau, Hameln, Nieubourg, &c. "Spandau," said he in the 19th Bulletin, "is an inestimable acquisition. In our hands it could sustain two months of operations. But such was the general confusion, that the Prussians had not even armed its batteries." The possession of these fortifications inclined the scale at Eylau. All the historians of the war notice their influence on the campaigns of Friedland and Tilsit.
These Prussian fortresses were retained by Napoleon at the treaty of Tilsit. The campaign of 1809 proved the wisdom of this policy, as they effectually prevented Prussia from joining Austria in rekindling the flames of war. And again in 1813, these works might have produced a decided influence on the campaign, had not the political perfidy of Austria, and the treason of the French generals, prevented Napoleon from profiting by the advantages of his position.
The influence of the fortifications of Spain upon the Peninsular campaigns has often been alluded to by historians. Those works which had been given up to Napoleon previous to the opening of hostilities, contributed very much to the success of his arms; while those which had been retained by Spain and her allies contributed in an equal degree to fetter and embarrass his operations. Some of these, like Saragossa, Tarragona, Gerona, Tortosa, &c. &c., with their broken walls and defective armaments, kept the enemy in check for months; and, by compelling the French to resort to the tedious operations of sieges, did much to weaken the French power in the Peninsula.
The influence of the fortifications of the French frontiers in furnishing a secure basis for the successful operations of Napoleon into the enemy's territory, has already been noticed. If these fortresses of France, after the disasters of 1812 and '13, failed to save the nation, the cause must be sought for in the peculiar features of the invasion itself, rather than any lack of military influence in the French defences. As has been already remarked, a million of disciplined men, under consummate leaders, were here assailing a single state, impoverished by the fatal war in Russia—torn in pieces by political factions—deserted by its sworn allies—its fortresses basely betrayed into the enemy's hands, and its military power paralyzed by the treason of generals with their entire armies. Its only hope was in the fortresses which had remained faithful; and Napoleon said at St. Helena, that if he had collected together the garrisons of these few fortresses and retired to the Rhine, he could have crushed the allies even after their entrance into Paris. But political considerations prevented the operation.
Again in 1815, Napoleon, even after the defeat of Waterloo, possessed lines of defence sufficiently strong to resist all attempts at invasion. But again the want of co-operation on the part of the government at Paris, and the treason of his own generals, forced his second abdication. If he had retained the command of the army, and the nation had seconded his efforts, the allies would never have reached Paris. But the new government presented the disgraceful spectacle of opening the way for the enemies of their country. "France," said Napoleon, "will eternally reproach the ministry with having forced her whole people to pass under the Caudine-forks, by ordering the disbanding of an army that had for twenty-five years been its country's glory, and by giving up to our astonished enemies our still invincible fortresses."
History fully supports Napoleon's opinion of the great danger of penetrating far into a hostile country to attack the capital, even when that capital is without fortifications. The fatal effects of such an advance, without properly securing the means of retreat, is exemplified by his own campaign of 1812, in Russia. If, after the fall of Smolensk, he had fortified that place and Vitepsk, which by their position closed the narrow passage comprised between the Dnieper and the Dwina, he might in all probability, on the following spring, have been able to seize upon Moscow and St. Petersburg. But leaving the hostile army of Tschkokoff in his rear, he pushed on to Moscow, and when the conflagration of that city cut off his hopes of winter quarters there, and the premature rigor of the season destroyed the horses of his artillery and provision-trains, retreat became impossible, and the awful fate of his immense army was closed by scenes of horror to which there is scarcely a parallel in history. This point might be still further illustrated by the Russian campaign of Charles XII., in 1708–9, the fatal advance of the French army on Lisbon, in the Peninsular war, and other examples of the same character.
Even single works sometimes effect the object of lines of fortifications, and frustrate the operations of an entire army. Thus, Lille suspended for a whole year the operations of Prince Eugene and Marlborough; the siege of Landrecies gave Villars an opportunity of changing the fortunes of the war; Pavia, in 1525, lost France her monarch, the flower of her nobility, and her Italian conquests; Metz, in 1552, arrested the entire power of Charles V., and saved France from destruction; Prague, in 1757, brought the greatest warrior of his age to the brink of ruin; St. Jean d'Acre, in 1799, stopped the successful career of Napoleon; Burgos, in 1812, saved the beaten army of Portugal, enabled them to collect their scattered forces, and regain the ascendancy; Strasburg has often been, the bulwark of the French against Germany, saving France from invasion, and perhaps subjugation.
In nearly the language of Napoleon, (Memoirs, vol. IX.,) If Vienna had been fortified in 1805, the battle of Ulm would not have decided the fate of the war. Again, in 1809, if this capital had been fortified, it would have enabled the Archduke Charles, after the disaster of Eckmuhl, by a forced retreat on the left of the Danube, to form a junction with the forces of General Hiller and the Archduke John.
If Berlin had been fortified in 1806, the army routed at Jena would have rallied there and been joined by the Russians. If Madrid had been strongly fortified in 1808, the French army, after the victories of Espinosa, Tudela, Burgos, and Sommo-Sierra, would not have marched towards that capital, leaving in rear of Salamanca and Valladolid, both the English army of General Moore and the Spanish army of Romana. If Moscow had been fortified in 1812, its conflagration would have been avoided, for, with strong defensive works, and the army of Kutusoff encamped on its ramparts, its capture would have been impossible.
Had not Constantinople been well fortified, the empire of Constantine must have terminated in the year 700, whereas the standard of the Prophet was not planted there until 1440. This capital was therefore indebted to its walls for eight hundred years of existence. During this period it was besieged fifty-three times, but only one of these sieges was successful. The French and Venetians took it, but not without a very severe contest.
Paris has often owed its safety to its walls. In 885 the Normans besieged it for two years without effect. In 1358 the Dauphin besieged it in vain. In 1359 Edward, king of England, encamped at Montrouge, devastated the country to its walls, but recoiled from before it, and retired to Chartres. In 1429 it repulsed the attack of Charles VII. In 1464 the Count of Charlerois surrounded the city, but was unsuccessful in his attacks. In 1472 it repulsed the army of the Duke of Bourgone, who had already ravaged its precincts. In 1536, when attacked by Charles V., it again owed its safety to its walls. In 1588 and 1589 it repulsed the armies of Henry III. and Henry IV. In 1636 and several succeeding years the inhabitants of Paris owed their safety to its walls. If this capital had been strongly fortified in 1814 and 1815, the allied armies would not have dared to attempt its investment.
But it is deemed unnecessary to further specify examples; the whole history of modern warfare is one continued proof of the importance of fortifications as a means of national defence, and as an auxiliary in offensive military operations. Our illustrations have been mostly drawn from European wars, but our own brief history, as will be shown hereafter, is not without its proofs.
The use and importance of field-fortifications, intrenched camps, &c., as well as the class of military works called coast-defences, will be discussed hereafter.[6]
