Treaty of Montgomery

Wales after the Treaty of Montgomery in 1267
  Gwynedd, Llywelyn ap Gruffudd's principality
  Territories conquered by Llywelyn
  Territories of Llywelyn's vassals
  Lordships of the Marcher barons
  Lordships of the king of England

The Treaty of Montgomery was an Anglo-Cambrian treaty signed on 29 September 1267 in Montgomeryshire by which Llywelyn ap Gruffudd was acknowledged as Prince of Wales by King Henry III of England (r. 1216–1272). It was the only time an English ruler recognised the right of a ruler of Gwynedd over Wales. Llywelyn's grandfather Llywelyn the Great had previously laid claim to be the effective prince of Wales by using the title "Prince of Aberffraw, Lord of Snowdon" in the 1230s, after subduing all the other Welsh dynasties. Likewise Llywelyn's uncle, Dafydd ap Llywelyn, claimed the title of Prince of Wales during his reign from 1240 to 1246. However, Llywelyn's supremacy in the late 1260s forced recognition of his authority in Wales by an English Crown weakened by internal division.

Conditions of the treaty

Many of the conditions of the treaty had been anticipated by the Treaty of Pipton (1265) between Llywelyn and Simon de Montfort. The 1267 treaty ceded Builth to Llywelyn, along with Brecon and Gwerthrynion in mid-Wales. Llywelyn was also granted Whittington Castle in modern-day Shropshire, previously held by his grandfather in the 1220s, and received an assurance that no castle would be built at Hawarden for sixty years by Robert of Mold, thus helping to secure the north-eastern border of Wales. 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.

The key text would be seen later by the Lord Edward as

“XIII. For the principality, lands, homages and grants the prince and his successors will be bound to give fealty, homage and service to the king and his heirs, which he or his predecessors have been accustomed and obliged to give the kings of England.”