A deserter brought in news of the exact position of his tent, and our artillery have been giving him such a peppering that, from the church tower, we see that he has been obliged to move his camp." As soon as it was night, four hundred cavalry were in the saddle.
Sarsfield placed himself at their head, and rode twelve miles up the Shannon to Killaloe.

Crossing the river there, he made a wide sweep with his cavalry, until he was in the heart of the Tipperary mountains, in rear of William's camp.
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.