 Parallel with the Welsh Wars , Hereford was also struggling to assert his claims to lands in the Marches against other Marcher lords . In 1284 Edward I granted the hundred of Iscennen in Carmarthenshire to John Giffard . Hereford believed the land belonged to him by right of conquest , and started a campaign to win the lands back , but the king took Giffard 's side . Problems also arose with the earl of Gloucester . As Gloucester 's former ward , Hereford had to buy back his own right of marriage , but Gloucester claimed he had not received the full sum . There was also remaining resentment on Hereford 's part for his subordination to Gloucester in the 1282 – 83 campaign . The conflict came to a head when Gloucester 's started construction of a castle at Morlais , which Hereford claimed was his land . In 1286 , the Crown ordered Gloucester to cease , but to no avail . 
