Château Gaillard was a fortress of far other importance than any of the castles which both parties had been so lightly winning, losing, and winning again, during the last ten years. It was the key of the Seine above Rouen, the bulwark raised by Richard Coeur de Lion to protect his favorite city against attack from France. Not till the fortifications which commanded the river at Les Andelys were either destroyed or in his own hands could Philip hope to win the Norman capital. And those fortifications were of no common order. Their builder was the greatest, as he was the last, of the "great builders" of Anjou; and his "fair castle on the Rock of Andelys" was at once the supreme outcome of their architectural genius, and the earliest and most perfect example in Europe of the new development which the crusaders' study of the mighty works of Byzantine or even earlier conquerors, quickened and illuminated as it was by the exigencies of their own struggle with the infidels, had given to the science of military architecture in the East. During the past year John had added to his brother's castle a chapel with an undercroft, placed at the southeastern corner of the second ward. The fortress, which nature and art had combined to make impregnable, was well stocked with supplies of every kind; moreover, it was one of the few places in Normandy which Philip had no hope of winning, and John no fear of losing, through treason on the part of its commandant. Roger de Lacy, to whom John had given it in charge, was an English baron who had no stake in Normandy, and whose personal interest was therefore bound up with that of the English King; he was also a man of high character and dauntless courage. Nothing short of a siege of the most determined kind would avail against the "Saucy Castle"; and on that siege Philip now concentrated all his forces and all his skill. As the right bank of the Seine at that point was entirely commanded by the castle and its neighbor fortification, the walled town--also built by Richard--known as the New or Lesser Andely, while the river itself was doubly barred by a stockade across its bed, close under the foot of the rock, and by a strong tower on an island in midstream just below the town, he was obliged to encamp in the meadows on the opposite shore. The stockade, however, was soon broken down by the daring of a few young Frenchmen; and the waterway being thus cleared for the transport of materials, he was enabled to construct below the island a pontoon, by means of which he could throw a portion of his troops across the river to form the siege of the New Andely, place the island garrison between two fires, and at once keep open his own communications and cut off those of the besieged with both sides of the river alike.