All however was in vain, and Oldcastle withdrew to his castle of Cowling, while Arundel summoned him before his court and convicted him as a heretic.

His open defiance at last forced the king to act.

In September a body of royal troops arrested Lord Cobham and carried him to the Tower; but his life was still spared, and after a month's confinement his imprisonment was relaxed on his promise of recantation.

Cobham however had now resolved on open resistance.

He broke from the Tower in November, and from his hiding-place organized a vast revolt.