CHAPTER III

GATES AND BRIDGES

Though confining ourselves to a brief historical abstract of the so-called Gothic period in architecture, without reference to Roman examples, we have said enough in the foregoing studies on castles and keeps, and the circumvallation of towns, to give some idea of the importance attached by architects to the gates which secured the _enceintes_, and the bridges which afforded an approach.

_Gates._--Following the example of those Frankish architects whose works in Syria after the first Crusade seem to have exercised such far-reaching influence, French builders of the reigns of Philip Augustus and St. Louis reduced the entrances of fortresses and fortified _enceintes_ to the smallest number practicable. Their construction was based upon a system calculated to repulse any ordinary attempt to carry the place by direct attack; as a rule, fortresses were taken rather by ruse, surprise, or treason than by regular siege.

During the twelfth, and more especially the thirteenth century, the gates were the points most strongly fortified. They were approached over a bridge, by raising a movable portion of which, however, entrance might be barred on the very threshold. The narrow gateway passage was defended by two projecting towers pierced with loopholes, and connected by a curtain. The whole structure formed a fortified gate-house, known as a _châtelet_, which had to be carried before an assailant could penetrate to the fortress beyond. The passage was further defended by a single or double portcullis, a grated timber framework like a harrow, cased with iron, the uprights of which were spiked at the bottom. The passage was also defended by machicolations or holes in the roof, through which the garrison could hurl down missiles on the heads of their enemies, should the latter have forced the gate.

The castle-gate of Carcassonne which was built about 1120 still exists, and is a good example of such arrangements.

The minute precautions adopted by architects to guard against surprise are very manifest in this example. A sudden attempt was often successful, especially if favoured by traitors among the defenders themselves.

The difficulties of passage were increased by the multiplication of portcullises, the windlasses of which were worked from different stories of the tower, so as to prevent collusion between different parties of the garrison, which was often composed largely of mercenaries. In the gate-house of Carcassonne the first portcullis was raised or lowered by means of chains and counter-weights worked from a windlass on the second floor; the second portcullis was worked in like manner from the first floor, in a place entirely cut off from communication with that above, to which access could only be obtained by a wooden staircase in the castle courtyard.

In the thirteenth century military architects further provided against surprises by defensive outworks. The gate of Laon, at Coucy, so admirably described by Viollet-le-Duc, is a famous example. These outworks, which were called barbicans, were designed to protect the great gate and its approaches.

Around the walls of the city of Carcassonne a second line of ramparts had been drawn by St. Louis, in which only a single opening gave access to the _lists_ (Fig. 187)--that is to say, the space between the inner and outer enclosures. He afterwards built a huge tower, known as the _Barbican_, to the west of the castle, with which it was connected by crenellated walls, and by inner cross-walls, so arranged in a kind of echelon that the open spaces on one side were masked by the projections on the other (see plan, Fig. 167). The tower was destined to cover sorties from the garrison, and to keep open communication by the bridge across the Aude. It was rather an outwork than a barbican such as Philip the Bold built before the _Porte Narbonaise_, on the east of the city, towards the close of the thirteenth century.

The _Porte Narbonaise_ bears a general resemblance to the main gate of the castle, subject, however, to the great advance made in military architecture in the course of a century. The gateway towers are provided with spurs, an invention directed against the attack of miners, which had the further advantage of interfering with the action of a battering-ram, by exposing those who worked it to missiles from the adjacent parts of the curtain. The gate opened immediately upon the lists; it was defended by the crenellated semi-circular barbican, which was united on either side to the embattled parapet of the lists. Access to the barbican was obtained only by a narrow passage preceded by a bridge, the latter easily defended by a redan which adjoined the postern of the barbican.

The gate itself was provided with two portcullises like those of the castle gate; behind the first were massive folding-doors, and over it a wide machicolation.

The constructive methods employed in the building of fortified gates were modified as military architecture progressed on lines already considered by us in the first chapter of this section, when dealing with defensive methods generally, which, in the fourteenth century, seem to have been in advance of those of attack. A steady improvement in details went on until the invention of gunpowder came in to profoundly modify the conditions alike of defence and assault.

The gateways of fortified _enceintes_ were modified in the fourteenth century not only by alterations in the plan of towers, the substitution of stone machicolations for the wooden _hourds_ or scaffoldings of parapets, the addition of portcullises, folding-doors, and the _machicoulis_ of the vaulted passage, but further by the invention of the drawbridge. A drawbridge, it may be hardly necessary to say, consisted of a wooden platform suspended by chains to cross-beams poised on uprights on the principle of a see-saw; when lowered, the bridge afforded a passage across the moat. It was raised by depressing the inner ends of the lever-beams which pivoted upon a fulcrum, and thus brought the platform up vertically against the front of the building, where it formed an outer door which an attacking party had either to batter in or to bring down by cutting the chains.

It will be readily perceived that such a bridge was infinitely more effectual and more to be depended upon than the portable bridge mentioned in our description of the castle gate of Carcassonne. The latter had to be raised piece by piece, a prolonged operation impossible of execution in case of a sudden surprise.

Aigues-Mortes seems to have been one of the first fortresses to which the new methods were applied. The gates east, west, and south are constructed on the twelfth-century system, as exemplified at Carcassonne. But the northern gate, known as the _Porte de la Gardette_, which was either made or altered in the fourteenth century, still shows the grooves for the beams of the drawbridge, and the pointed arch of the doorway is enframed by a square rebate destined for the platform when raised.

The use of drawbridges became very general in the fourteenth century, and gave rise to various ingenious combinations. The gate at Dinan, known as the _Porte de Jerzual_, which probably dates from the close of the century, is a curious example. It is not placed between two towers in the manner then usual, but is pierced through the actual face of a tower. In this case, the inner prolongation of the lever-beams formed a solid panel like the platform of the bridge itself. It was worked through a hole in the roof of the entrance archway, being raised with the help of a chain, and falling through its own preponderant weight. The horizontal pivot on which it turned rested on the brackets shown in Fig. 190; the external sections of the lever-beams sank in the usual manner into the vertical grooves above the arch, and when the bridge was up, the solid panel joining the inner ends of the levers doubled the protection it gave. In case of alarm, the chain had simply to be let go, and the panel falling by its own weight, the bridge rose, and the barricade was complete.

By the fifteenth century drawbridges were in universal use; an interesting development was the result. This was the introduction of a smaller gate or postern in the curtain between the towers, by the side of the great gateway. Each of the two apertures was furnished with its own drawbridge. That of the centre, which was reserved for horsemen and vehicles, was worked by two beams or arms, as we have seen, while the smaller footbridge of the postern was raised by means of a single beam, the chain of which was attached to a forked upright.

The castle of Vitré, which was built, or at least completed at the close of the fourteenth or beginning of the fifteenth century, illustrates the system in the gateway of its _châtelet_.

The gate-house, known as the _Porte St. Michel_, at Guérande, which was built together with the _enceinte_ by John V., Duke of Brittany, in 1431, still preserves the lateral grooves which indicate the shape and arrangement of the postern drawbridge.

When raised, the two drawbridges closed the apertures of gateway and postern, while the open gulf of the great ditch, either empty, or full of water, cut off the approach to the entrance.

The Abbey of Mont St. Michel, which we have already studied under various aspects, has further information to give us with regard to the construction of fortified gateways. In accordance with contemporary usage, the Abbot Pierre Le Roy built a gate-house or _bastille_ (Fig. 163), the entrance of which was guarded by a portcullis and a wide _machicoulis_; he masked this gate-house by a barbican, which was connected north and south with the great stairway leading to the abbey. The northern staircase is rendered specially interesting by the ingenious arrangement of its gates, which opened within the barbican. The apertures were filled by a panel which worked horizontally, on a system necessitated by the exceptional situation of the abbey, where the military, as well as the domestic buildings, were superposed, communicating with each other only by an elaborate series of staircases and inclines. The doors pivoted upon horizontal axes. Resting upon salient jambs in the embrasures of the doorways, they opened in a direction parallel with the slope of the steps, and could be shut at the least alarm, being carried into place by their own weight. They were kept fastened by lateral bolts, the slots of which still exist in the jambs.[68]

[68] Ed. Corroyer, _Description de l'Abbaye du Mont St. Michel et de ses Abords_; Paris, 1877.

The main gate of the ramparts, which was built between 1415 and 1420, is to the west of the place, in the curtain flanked by the tower known as the _Tour du Roi_. This gate and the lateral postern gave access to the town, their drawbridges forming a passage across the moat when lowered, and when raised, an initial barrier to assailants. Above the gates was the warder's lodging, beneath which the vaulted passage and the postern communicated directly with an outer guard-room in the ground-floor of the _Tour du Roi_. In addition to the first barrier, formed by the raised platform of the drawbridge, the main entrance was secured by double doors, and by an iron portcullis, which still remains in its lateral grooves. The great arch is crowned by a tympanum, on which the united arms of the king, the abbey, and the town were carved.

The works designed for the defence of rivers flowing through fortified towns, or of the inlets of harbours, are closely allied to the military architecture of gates. At Troyes the river arches in the town ramparts were guarded by gratings or portcullises of iron. At Paris the passage of the Seine was barred by chains stretched across the river from wall to wall, and upheld in the middle of the stream by piles or firmly anchored boats. At Angers the walls of the town abutted on two towers known as the _Haute Chaîne_ and the _Basse Chaîne_ (the Higher and Lower Chains), containing windlasses for the chains, which at night were stretched across the Maine at its passage through the _enceinte_.

Seaports were defended at the mouth by towers on either shore, between which chains, worked from within, could be stretched to bar the passage. The harbour of La Rochelle is thus protected. According to some archæologists of authority, the tower known as the _Tour de la Chaîne_ (to the left of the drawing) is older than that of St. Nicholas (on the right), which is supposed by them to have been built in the sixteenth century on the foundations of an earlier tower contemporary with that on the other side of the Channel. The piles upon which these towers stand seem to have given way in part, and to have caused a perceptible inclination of the Tower of St. Nicholas.

The suggestion made in a very fanciful modern design, that the two towers were once united by a great arch, is wholly without foundation. Such a useless structure would have entailed defensive works equally useless, seeing that a chain stretched from tower to tower at high tide--at low tide the harbour was inaccessible--would have been perfectly effectual against any vessels of that period attempting to force a passage.

_Bridges._--As is the case with all other architectural buildings, the origin of bridges dates back to the Romans, by whom they were often decorated with triumphal arches. The bridge of St. Chamas in Provence, known as the _Pont Flavien_ (Flavian Bridge), is an example which seems to date from the first centuries of the Christian era.

The triumphal arches were in later times replaced by fortifications; they became _têtes de pont_, _bastilles_, or crenellated gate-houses, the function of which was not, like that of the arches, the decoration of the structure or the glorification of its founder, but the defence of the passage across the river, and the protection of the fortress with which it communicated.

Among the bridges constructed by mediæval architects, that of St. Bénézet, the Bridge of Avignon, seems to be the most ancient. This bridge, which was begun about 1180, and completed some ten years later, is equally remarkable for its architectural details, and the structural problems solved by its builders. It crosses, or rather used to cross, the Rhone--for though the arm towards the _Rocher des Doms_ is the narrower, it is the deeper--on nineteen arches, extending from the foot of the Doms, on the Avignonese bank, to the Tower of Villeneuve, on the right bank, after a slight deflection southward.

The gate-house on the left bank, some fragments of which still remain, is said to have been built by the Popes in the fourteenth century, for the purpose of levying tolls, a perquisite shared by them with the King of France.

The Bridge of Avignon seems to have been one of the first constructed by the fraternity of the _Hospitaliers pontifs_, which was founded in the twelfth century for the double object of building bridges and succouring travellers. The head of the order at the time of the building of the Rhone bridge was St. Bénézet. It must have numbered architects of ability among its members, for the construction of the Bridge of Avignon is very remarkable. Each of the elliptical arches is composed of four independent arches in simple juxtaposition one with another. This device ensures elasticity, and as a consequence stability. The solidarity of the whole is rendered complete by the masonry of the spandrils, which recall the architectural portions of the aqueduct, known as the _Pont du Gard_; its width is about 16 feet. The arches spring from piers furnished on either face with acute spurs designed to break the force of the stream and the impact of floating ice in the winter.

The spandril above each pier is pierced with a round arch, to give free passage to the water during those floods which at times completely submerge the piers.

The bridge in its present ruined condition has only four arches. On the pier nearest to the left bank the ancient chapel, dedicated to St. Nicholas, is still standing. Access to it is obtained by means of a flight of corbelled steps rising from the foundation to the entrance, and by an overhanging landing-stage, resting at one end against the pier, at the other against the flank of the arch.

The old bridge at Carcassonne seems to be contemporary with that of Avignon, but its arches are semi-circular, their keystones are bound into the intrados, and their piers are spurred to the level of the platform, where they form recesses or refuges, which the narrowness of the bridge rendered very necessary.

Among bridges of the thirteenth century we may mention that at Béziers, where the arches, both pointed and semi-circular, resemble those of Carcassonne in construction; but here the piers only rise above the summers of the arches by the height of two or three courses, and their spandrils are pierced to give free passage to the current during floods.

The bridge which spanned the Rhone at St. Savournin du Port, known as the _Pont St. Esprit_, was the work of a Clunisian abbot about 1265. It resembled the Bridge of Avignon in the construction of the piers with their pierced spandrils; the arches, however, were semi-circular. The platform, which is some 16 feet across, was barred at either end by toll-gates; that nearest to the little town was connected with the _tête de pont_, which, in after times, was incorporated with the fortress commanding the course of the Rhone above the bridge.

The question of tolls was an important one in those days, and gave rise to frequent disputes. The towers and gate-houses of bridges were toll-bars as well as defensive outworks.

The bridge at Montauban, known as the _Pont des Consuls_, which was begun at the close of the thirteenth century, remained unfinished till the beginning of the fourteenth, when Philip the Fair gave such help as was needed for its completion, on condition that he should be allowed to raise three towers on the bridge, with a view to the appropriation of the tolls.

The Bridge of Montauban is built entirely of brick. It consists of seven pointed arches, resting on spurred piers, which are pierced with arches, also pointed, and rising to the same height as the main arches, to provide for the frequent floods of the Tarn.

The Bridge of Cahors is one of the most beautiful of fourteenth-century examples. It is still of great interest in spite of the various restorations it has undergone, chiefly of late years.

This bridge, which is known as the _Pont de Valentré_, was begun in 1308 by Raymond Panchelli, Bishop of Cahors from 1300-1312, and cannot have been finished before 1355. It consists of six slightly pointed arches; the piers, which rise to the level of the parapet, forming lateral refuges, are triangular above bridge and square below. At each end the bridge was commanded by a crenellated structure, forming a gate-house or _tête de pont_ on either bank. In the middle rose a lofty tower with gates, by means of which passage might be barred and assailants checked in the event of a surprise of either gate-house.

The Bridge of Orthez has strong affinities with that of Cahors. It must date from about the same period, and there is every reason to suppose it was defended, not only by the central tower, but by _têtes de pont_, one of which at least must have been destroyed to make way for the railroad from Bayonne to Pau.

Bridges were of great importance in the Middle Ages, both as public highways and military outworks. At certain points, notably at the confluence of two rivers, they were strongly reinforced by very considerable defences, as at Sens, Montereau, etc.

At Paris, Orleans, Rouen, Nantes, and a large number of other towns traversed by rivers, bridges were not only important as military defences, but of great interest as architecture.

Mont St. Michel shall furnish us with our last example, a bridge of the fifteenth century. Though it spans no stream, it is none the less remarkable. In the details of this bridge--its embattled platform uniting the lower church to the abbey, its machicolated parapet guarding the inner passages--we recognise an art consummate as that which stirs our enthusiasm in the vast proportions and perfect execution of the splendid choir, the whole proclaiming the versatile genius of those great builders who welded into one noble monument a triad of masterpieces--religious, monastic, and military.