In the second bay of the north aisle, a gallery (_B on plan_), the remains of the old cathedral cloister, gave access to a large chapel (Chapelle des Œuvres) with two naves of three bays. It was the old chapter-house, built in the 13th century, by prolonging the west front but completely remodelled in the 19th century. [Illustration: THE NAVE BEFORE THE BOMBARDMENTS.] [Illustration: COLLAPSE OF THE PILLAR, FEBRUARY 1915.] [Illustration: SOUTHERN AISLE AND TRIFORIUM, NOVEMBER 1918.] The destruction of the Nave and fall of the Pillar. Early in February 1915, a projectile, entering by a hole made by a previous shell in the wall of the south aisle, struck the second column (_A on plan, p. _18) on the left of the main nave, which was broken in two about 13 feet from the ground (_photos pp. _20–21). The upper part, with the capital and courses supporting the springing of the vault, gave way, dragging down in its fall a portion of the vault and of the wall at the back of the triforium. The ruins accumulated rapidly. By the end of March, the roof of the grand nave and of the north aisle, which the broken pillar had sustained, collapsed. The whole of the triforium, the large window, the flying buttress outside, the framework, and the roofing of the bay of the aisle also gave way. An enormous breach was made in the cathedral, and the floor of the nave was covered with a shapeless mass of broken stones, which increased during the following months. [Illustration: THE GREAT NAVE AND NORTHERN AISLE, NOVEMBER 1918. _Behind the two standing pillars is seen the base of the pillar which collapsed in Feb. 1915. The fall is shown on p. _20.] [Illustration: THE FALLEN VAULTING LEFT BARE THE DAMAGED FRAMEWORK OF THE ROOF.] [Illustration] [Illustration: BREACH IN THE NAVE, NOVEMBER 1918.] The fall of the Vaulting. The vaults of the remaining bays, already weakened, could not withstand the renewed bombardments. One after another they crashed to the ground, with the exception of those of the first and seventh bays. Everywhere else, pieces of broken or disjointed framework, supporting a completely ruined roof, are exposed to view (_photo above_). Several of the large windows on the north side have also fallen in and all the stained-glass has been smashed. The Final Ruin. [Illustration: THE NAVE, AUGUST 1918.] The bombardments of 1918 destroyed the nave beyond hope of repair. Several large pillars collapsed and a considerable portion of the upper part of the side walls, large arches and triforium fell in to the right and left. Three bays near the west front, with their large arches and the aisles were completely destroyed. All this masonry fell inside the nave, forming across its entire breadth a heap of debris more than 19 feet high and about 33 feet long.