Elements of Military Art and Science. H. W. Halleck
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