The affair is serious, and unless the king comes hither with an army, Glendower is likely to have it all his own way on his side of the border; and, ere long, there won't be an Englishman left west of the Severn." However Henry, when informed of the danger, lost no time in assembling another great army; and in the beginning of June advanced into Wales, and ravaged a wide extent of country, carrying his arms into Cardiganshire, and destroying the Abbey of Strata Florida, one of the most venerable and famous abbeys in Wales.

Founded in 1164, it was burnt down in 1294, during the wars of King Edward the First with the Welsh, but was soon rebuilt.

Here Llewellyn, in 1237, convened all the chieftains of Wales to take the oath of allegiance.

There were two copies of the national records, one of which was kept at this abbey, and the other at that of Conway.
The abbey having fallen, Henry's army met with scarcely any resistance, Glendower knowing that his wild followers were no match for the royal troops.

He therefore contented himself with harassing them continually, and the army suffered greatly by this continued annoyance, as well as from fatigue and famine.