Treaty of Montgomery

However, Llywelyn's supremacy in the late 1260s forced recognition of his authority in Wales by an English Crown weakened by internal division.

The treaty also allowed for the reinstatement of Llywelyn's brother, Dafydd ap Gruffudd, into Welsh society after his defection to England in the early 1260s.

Though the treaty required Llywelyn to do homage to the king of England for the land, it was in effect an acknowledgement of the power and authority of the prince.

However, after the succession of Edward I as king of England in 1272, relations between England and Wales deteriorated, and Edward declared war on Llywelyn in 1276; the Treaty of Aberconwy of 1277 superseded the stipulations laid down at Montgomery and severely curbed Llywelyn's power.

After 1295 and the final Welsh War of the thirteenth century, the castle became more of a military backwater and prison than a front line fortress.

Coloured map depicting Wales (adjacent to the Kingdom of England, coloured dark orange) following the Treaty of Montgomery of 1267. Gwynedd, Llywelyn ap Gruffudd's principality, is green; the territories conquered by Llywelyn are purple; the territories of Llywelyn's vassals are blue; the lordships of the Marcher barons are shown as light orange; and the lordships of the King of England are shown in yellow.
Wales after the Treaty of Montgomery of 1267:
Gwynedd , Llywelyn ap Gruffudd's principality
Territories conquered by Llywelyn ap Gruffudd
Territories of Llywelyn's vassals
Lordships of the Marcher barons
Lordships of the King of England
Kingdom of England