Quietly as the expedition had been carried out, it was impossible that so large a body of horse should ride through the country unperceived, and a gentleman of county Clare, named O'Brian, thinking that he would gain honour and advantage by reporting their passage to William, set out for the British camp. Being unknown there, he was a long time before he could get access to the king. The officers to whom he spoke paid little attention to his story about a body of Irish horse passing through the country, and were much more interested in gaining information from him as to the state of the stock of cattle, sheep, and pigs in his part of the county; for, owing to the terror excited by the conduct of William's soldiers, the people for many miles round had driven off their stock and left the villages, and provisions were already becoming scarce in the camp. At length, however, one of those to whom he had spoken mentioned his story to the king, who at once sent for him, and saw the importance of the news he brought. O'Brian himself had no idea of the object of Sarsfield's expedition, but the king instantly guessed that it was the siege train. He therefore ordered a large body of cavalry to be immediately despatched to meet the artillery on its way, and protect it into camp. All day, Sarsfield remained in concealment among the mountains, until, towards evening, the train came in sight, moving slowly with its escort of two troops of dragoons along the high road. He watched it until it halted, and encamped for the night, in a field beside the highway. He waited until the horses were picketed, and the men engaged in making their encampment for the night. Then the Irish cavalry burst down from the glen in which they had been hiding. The officer in command sounded to horse, but it was too late; before the men were in the saddle, the Irish were upon them, and in a moment the two troops of dragoons were dispersed or killed. Sarsfield's men at once set to, to collect the powder waggons, pontoons, and baggage of every description. The great guns were filled with powder to the muzzle, and then buried two-thirds of their length in the earth. The whole mass of siege equipage was piled above them, and a train of gunpowder was laid to the store in the centre. The men then drew off to a distance. A match was applied to the train, and the whole blew up with a tremendous explosion.