Meanwhile Quitman had stormed the batteries on the causeway to the east of the castle, after a desperate struggle, in which Major Twiggs, who commanded the stormers, was shot dead at the head of his men. The Mexicans fell back toward the city. General Scott, coming up at this moment, ordered a simultaneous advance to be made on the city along the two roads leading from Chapultepec to the gates of San Cosme and Belen respectively. Worth was to command that on San Cosme, Quitman that on Belen. Both were prepared for defence by barricades, behind which the enemy were posted in great numbers. Fortunately for the assailants, an aqueduct, supported on arches of solid masonry, ran along the centre of each causeway. By keeping under cover of these arches and springing rapidly from one to another, Smith’s rifles and the South Carolina regiment were enabled to advance close to the first barricade on the Belen road and pour in a destructive fire on the gunners. A flank discharge from Duncan’s guns completed the work; the barricade was carried; and, without a moment’s rest, Quitman advanced in the same manner on the garita of San Belen, which was held by General Torres with a strong garrison. It, too, was stormed, though under a fearful hail of grape and canister; and the rifles moved forward toward the citadel. But at this moment Santa Anna rode furiously down to the point of attack. Boiling with rage at the success of the invaders, he smote General Torres in the face, threw a host of infantry into the houses commanding the garita and the road, ordered the batteries in the citadel to open fire, planted fresh guns on the Paseo, and infused such spirit into the Mexicans that Quitman’s advance was stopped at once. A terrific storm of shot, shells, and grape assailed the garita, where Captain Dunn had planted an eight-pounder. Twice the gunners were shot down, and fresh men sent to take their places. Then Dunn himself fell, and immediately afterward Lieutenant Benjamin and his first sergeant met the same fate. The riflemen in the arches repelled sallies, but Quitman’s position was precarious till night terminated the conflict.