They met on the border in a narrow valley at Pilleth, near Knighton, and during the battle the Welsh tenants went over in a body to the side of Glyndwr. Eleven hundred men were killed, and Mortimer was captured.
Then ensued the dispute between Harry Hotspur and King Henry which has been immortalised by Shakespeare. Henry Percy’s wife was the sister of Sir Edmund Mortimer, and he was urgent for the ransoming of the captive. But King Henry was in sore straits for money, and he was, moreover, not particularly desirous to have the uncle of the true heir to the throne at large. What he did was to lead an army a third time into Wales, whilst a second was placed under the command of the Prince of Wales, and a third under that of the Earl of Warwick.
“Never within man’s memory had there been such a September in the Welsh mountains. The very heavens themselves seemed to descend in sheets of water upon the heads of these magnificent and well-equipped arrays. Dee, Usk, and Wye, with their boisterous tributaries that crossed the English line of march, roared bank-high, and buried all trace of the fords beneath volumes of brown tumbling water, while bridges, homesteads, and such flocks as the Welsh had not driven westward for safety were carried down to the sea.”[7]
Numbers died of exposure; the King’s tent was blown over upon him; and just a fortnight after having entered Wales in all the pomp and circumstance of war, the armies had to retreat, baffled, draggled, and dispirited, and fully persuaded that their great adversary was in league with the Spirit of Evil.
Meanwhile a friendship had sprung up between Mortimer and his captive, quickened by resentment against Henry, who had refused to ransom him, and this led to a closer tie, for he married Glyndwr’s fourth daughter, Joan.
Meantime, also, the anger of Harry Hotspur against the King had reached a head. He allied himself with the Scots, and marched upon Shrewsbury, unhappily for him without having concerted a plan of operations with Owen, who was away in the South of Wales, and unaware that the fiery Percy was about to engage the King.
Tradition will have it that Glyndwr hastened towards Shrewsbury, and watched the battle from a tall oak on the Welsh road from Shrewsbury, and made no attempt to strike at Henry from the rear. But this is false. Glyndwr, at the time, was in Carmarthen in total ignorance of the movements of Harry Percy.
The defeat of Shrewsbury was disastrous to the cause of the Welsh. Owen, having lost the assistance of his northern ally, entered into negotiations with the French, who sent him some aid, which was not very effective, and from this time his power began to decline. Now it was that Owen summoned a parliament of the Welsh to meet at Machynlleth, consisting of four persons of consequence out of every Cantref in the Principality.
One of those attending it was David ab Llewelyn, nicknamed Gam, or the “squint-eyed,” a little red-haired, long-armed, unprincipled man, who had been in the household of John of Gaunt. He was a native of Brecon, no relation to Owen, though he knew him intimately, and was trusted by him. Whether at the instigation of King Henry, or moved thereto by his own treacherous heart, we know not, but he framed a plot for the assassination of Owen during the conclave. One of the conspirators betrayed the design, and David Gam would have been executed but that his Brecon friends and relations intervened. Owen Glyndwr consented to remit the extreme penalty, and sent him for confinement in prison at Dolbadarn.