Besieged Moors repaired walls nightly and held out against cannons for months

Evidence

The Moors took up strong defensive positions, so that it was necessary to bring up much artillery, and attack them with determination. However, those parts of the wall that the cannons could knock down in the daytime were carefully repaired during the night by the Moors, so the Christians in the morning found the parts they had damaged in good repair. The commander found himself in a difficult situation, for the artillery was of little avail, and the weather conditions were severe, it being midwinter. Unable to think of any other tactic, he was advised that the water cistern, the only one for the whole village, might be undermined. He ordered the work to be commenced, and had such good success that within a week they had drained it completely. The Moors, finding themselves without a water supply, had just decided to surrender when it snowed very hard, and they thought they would have supplies for some time. They were mistaken, for there was only enough water for a week, so they asked to negotiate, and Fernando de Zafra came to speak in the king’s name. However, all terms were refused other than surrender at the king’s mercy. The siege of this place lasted three months, and the besiegers suffered great hardships because of the snow and cold, from which many of them died, and others lost arms or legs from frostbite. — L. P. Harvey, Muslims in Spain, 1500 to 1614, 235

Categorization

• QUESTION: The relief of hoping for snow then realising melted snow gives only about a week of water — I’d want to understand the hydrology of how a drained cistern could still fill from snowmelt, and whether this reflects siege engineering knowledge worth chasing.