He founded Burnham Abbey in Buckinghamshire in 1263, and the Grashaus, Aachen in 1266.

He joined King Henry in fighting against Simon de Montfort's rebels in the Second Barons' War (1264–67).
After the shattering royalist defeat at the Battle of Lewes, Richard took refuge in a windmill, was discovered, and was imprisoned until September 1265.

Richard bought the feudal barony of Trematon in 1270.

In December 1271, he had a stroke.
His right side was paralysed and he lost the ability to speak.
On 2 April 1272, Richard died at Berkhamsted Castle in Hertfordshire.
He was buried next to his second wife Sanchia of Provence and Henry of Almain, his son by his first wife, at Hailes Abbey, which he had founded.

After his death, a power struggle ensued in Germany, which only ended in 1273 with the emergence of a new Roman King, Rudolph I of Habsburg, the first scion of a long-lasting noble family to rule the empire.
In Cornwall, Richard was succeeded by Edmund, son of his second wife Sanchia.
He founded Burnham Abbey in Buckinghamshire in 1263, and the Grashaus, Aachen in 1266.
He joined King Henry in fighting against Simon de Montfort's rebels in the Second Barons' War (1264–67). After the shattering royalist defeat at the Battle of Lewes, Richard took refuge in a windmill, was discovered, and was imprisoned until September 1265.
Richard bought the feudal barony of Trematon in 1270.
In December 1271, he had a stroke. His right side was paralysed and he lost the ability to speak. On 2 April 1272, Richard died at Berkhamsted Castle in Hertfordshire. He was buried next to his second wife Sanchia of Provence and Henry of Almain, his son by his first wife, at Hailes Abbey, which he had founded.
After his death, a power struggle ensued in Germany, which only ended in 1273 with the emergence of a new Roman King, Rudolph I of Habsburg, the first scion of a long-lasting noble family to rule the empire. In Cornwall, Richard was succeeded by Edmund, son of his second wife Sanchia.
Richard of Cornwall