The old spirit of independence flickered once again when Owen Glendower marched to Brecon in 1403.
The king marched against him in person in 1400 and 1401, but Glendower showed himself a master of guerrilla warfare; he refused battle, and defied pursuit in his mountains, till the stores of the English army were exhausted and Henry was forced to retire.
In July 1403 came the crisis of King Henrys reign; while Glendower burst into South Wales, and overran the whole Insurrec- countryside as far as Cardiff and Carmarthen, the tion In the Percjes raised their banner in the North.
Old commercial disputes and the support which the French had lent to Glendower gave a sufficient excuse for war, whilst the disordered state of France afforded no security for peace.
Outside the north-west angle of the castle, Richard de Clare in 1256 founded a Dominican priory, which was burnt by Glendower in 1404.
In 1404 Owen Glendower burnt the town, except the quarters of the Friars Minors.
In the centre is Cadair Rhys Goch o'r Eryri, a rock named as the chair of Rhys Goch, a bard contemporary with Glendower (died traditionally, 1420).
In vain did Henry and his lords-marchers endeavour to suppress the rebellion, and to capture, by fair means or foul, the person of Glendower himself; the princely adventurer seemed to bear a charmed existence, and for a few years Owen was practically master of all Wales.