Marcher lordships were set up just after the Norman conquest of England to try and keep the Welsh under control.
Given to the English king's most trusted nobles, the lords who ruled these areas were given special powers that were usually reserved for the king. The marcher lordships were among the heaviest fortified areas in all of Europe, and also among the most brutal.
In the 200 years, it took the Normans to subdue the Welsh these Marcher Lords committed some brutal acts which alone caused many rebellions and many of these lords being detested and killed.
One example of the Brutality of the Marches was the so-called Abergavenny massacre.
Seisyll ap Dyfnwal Lord of Gwent Uwchcoed along with all the other Welsh princes and leaders from the area was invited to Abergavenny Castle at Christmas by William De Braose. Some Welsh leaders stayed away, mistrusting de Braose but Seisyll attended along with his eldest son Geoffrey. Most other leaders followed suit and attended, assured of peaceful intent at the castle and surrendering their arms.
Once the guests were all assembled inside the great hall, the doors were barred and all were slaughtered. William and his men then jumped onto their horses and sped south to the country of Seisyll ap Dyfnwal and executed the youngest son, seven-year-old Cadwaladr, in his mother's arms.
De Braose himself earned the nickname the 'Ogre of Abergavenny' for his conduct and his follow-up retribution on his enemy's families.
Seisyll's death was avenged in 1182 by Hywel ap Iorwerth in a campaign in which the sheriff of Hereford was killed and Abergavenny castle stormed.
