Meanwhile, since doubts were felt as to the main operation of storming the new breach, No. III, subsidiary efforts were made to incommode the enemy in other ways. At intervals on the 9th, 10th, and 11th red-hot shot were fired at the church of Santa Maria la Blanca, where it was known that the French magazine of food lay. The experience of the Salamanca forts had led the artillery officers to think that a general conflagration might be caused. But the plan had no success; the building proved to be very incombustible, and one or two small fires which burst out were easily extinguished. Another device was to mine out from the end houses of the city towards the church of San Roman, an isolated structure lying close under the south-east side of the Castle, which the French held as an outwork. Nothing very decisive could be hoped from its capture, as if taken it could only serve as a base for operations against the two _enceintes_ above it[52]. But, as an eye-witness remarked, at this period of the siege any sort of irregular scheme was tried, on the off chance of success. By October 17 the mine had got well under the little church. A more feasible plan, which might have done some good if it had succeeded, was to run out a small mine or fougasse from the sap-head of the trench in front of breach I to the palisades of the second _enceinte_. It was a petty business, no more than two barrels of powder being used, and only slightly damaged an angle of the work in front when fired on October 17. An attempt to push on the sap after the explosion was frustrated by the musketry fire of the besieged. On the 18th the engineers reported that the church of San Roman was completely undermined, and could be blown up at any moment. On the same morning the one good and two lame 18-pounders in battery 2 on San Miguel swept away, not for the first time, the sandbag parapets and _chevaux de frise_ with which the French had strengthened the breach III. They were then turned against the third _enceinte_, immediately behind that breach, partly demolished its ‘fraises,’ and even did some damage to its rampart. This was as much as could have been expected, as the whole of the enemy’s guns were, as usual, turned upon the battering-guns, and presently obtained the mastery over them, blowing up an expense-magazine in No. 2, and injuring a gun in No. 1. But in the afternoon the defences were in a more battered condition than usual, and Wellington resolved to make his last attempt. Already the French army outside was showing signs of activity; and, as a precaution, some of the investing troops--two brigades of the 6th Division--had been sent forward to join the covering army. If this assault failed, the siege would have to be given up, or at the best turned into a blockade.