The 18th of April was one of the most memorable days of the siege. The Persian batteries opened before noon, with unwonted activity, against the ramparts behind the great mosque. The walls soon began to crumble beneath the heavy fire of the enemy. First the thin parapets fell; then the _terre-plein_ came down; “the old walls sliding into masses at every round.”[174] Before evening, on the eastern and northern sides, the breaches were practicable, and that on the west was greatly enlarged. But the Afghans were in no way disheartened. They saw their walls crumbling beneath the heavy fire of the Persian batteries, and were neither alarmed nor discouraged by the spectacle. They had never trusted, they said, to their walls. The real defence, they declared, was the _fausse-braie_. About noon the Persians, having pushed on a gallery at this point, the garrison exploded it with a mine, and taking advantage of the alarm occasioned by the explosion, the Afghans rushed upon the besiegers, and at first carried everything before them. But in a short time the trenches of the enemy were lined with musketeers. The small-arm fire of the Persians overwhelmed that of the garrison, whilst the breaching batteries resumed their fire against the wall. Yar Mahomed and Pottinger were both upon the works. The Wuzeer ordered the men to cease firing, and to sit down, that they might be sheltered from the storm of musket-balls; but instead of this they drew their swords, brandished them over their heads, and calling to the Persians to come on, rushed down to the attack. They paid dearly for this bravado.[175] Pottinger himself narrowly escaped a bullet, which entered the lungs of Aga Ruhem, a favourite and devoted eunuch of Yar Mahomed, and sent him to his grave.