Escaping from Scotland, where he feared that he might be seized and surrendered to England, the earl sailed to Wales, and for some little time stayed with Glendower; then he crossed to the Continent, and in 1408 landed in Yorkshire and again raised his standard. The sheriff of the county called out the levies, and attacked him at Branham Moor, where the old earl was killed and his followers defeated.
In 1415 the king, being on the eve of war with France, and anxious to obtain the goodwill and support of the Northumbrians, restored Hotspur's son, who had been for years a fugitive in Scotland, to the estates and honours of his father and grandfather.
Fortunate it was, for Oswald, that the capture of his fellow conspirators caused the earl to retreat, in 1405, without giving battle. The young knight had, at his summons, called out his tenants, and with them and his retainers had joined Percy. As soon as the latter decided to fly to Scotland, his force scattered, and Oswald returned home with his following.
He took no part in the final rising. Before this took place he had married his cousin, Janet. His father lived to be present at the wedding, but died the following year; and, in accordance with his wishes, Oswald took up his abode at Yardhope, which he largely added to, and strongly fortified. Here his mother lived with him until her death, ten years later.
Oswald offered to Roger the command of his castle at Stoubes, but the burly squire preferred staying at Yardhope, with his master. He himself had taken a wife, the daughter of one of the principal tenants on the estate, on the same day that Oswald married Janet.
His uncle, after the surrender of Alnwick, lived at Yardhope until, at the return of Hotspur's son as Earl of Northumberland, he resumed his old position as captain of the garrison, and maintained it until his death.