Although Fitzhamon was an actual historical figure, 16th-century historians, in particular Sir Edward Stradling, built upon the legend of a group of knights who ruled over the county in his stead.
The fact that many of the knights existed during the period gave the legend credence.
[1] In 1561, he wrote "The Winning of the Lordship of Glamorgan out of Welshmens' Hands", describing the actions of Robert FitzHamon, the first Lord of Glamorgan, assigning to him twelve Knights who followed him from Gloucestershire to effect the conquest.
It has been more recently determined that the first Stradling in Glamorgan actually arrived later than Fitzhamon, probably originating in Switzerland.
[2] An account of the Knights and of the stolen lands allotted to each by right of conquest is given in the 1591 work of Sir Edward Mansel of Margam, "An Account of the Cause of the Conquest of Glamorgan by Sir Robert FitzHaymon and his Twelve Knights".