Owen Glendower (glĕnˈdouˌər, glĕndouˈər) [key], Welsh Owain Glyndwr, 1359?–1416?, Welsh national leader. A scion of the princes of Powys, he was also claimant through his mother to the lands of Rhys ap Gruffydd; he was thus one of the most powerful lords in Wales. After studying law in London and fighting in the English army, he returned to Wales. In 1400 he emerged as the leader of a revolt against English rule. The immediate occasion was a quarrel with his neighbor Lord Grey of Ruthin, an English border baron; but deeper causes of the national upheaval that followed lay in Welsh antagonism toward their English overlords, Welsh resentment of unjust English laws and administration, and widespread economic discontent. Owen, proclaimed (1400) prince of Wales by his followers, kept the revolt against Henry IV of England burning for years. In 1402 he captured Sir Edmund de Mortimer, whose nephew the 5th earl of March had a claim to the English throne, and secured his support. He then allied himself with the discontented Percy family (Sir Henry Percy; his father, Henry Percy, 1st earl of Northumberland; and Thomas Percy, earl of Worcester). The defeat of the Percys at the battle of Shrewsbury in 1403 (in which Owen did not take part) was only a temporary setback for the Welsh leader. The following year he displayed his skill as a daring guerrilla fighter by capturing the key castles of Aberystwyth and Harlech. He was recognized by Charles VI of France, with whom he made (1404) an alliance, and summoned (1405) his own parliament. However, the failure of an expedition from France on his behalf (1405–6) weakened him, and the recapture by the English of Aberystwyth (1408) and Harlech (1409) left him powerless. He disappeared into the mountains and refused to take advantage of the general amnesty offered by Henry V.
See biography by G. Williams (1966).