The chroniclers emphasize the fact that this king was not of royal descent.
The chroniclers of the conquest of Apulia and Sicily use the Norman name in every page as the name of the followers of the conquerors from Hauteville.
Later chroniclers indulged in the fictitious and the marvellous, and it is almost exclusively from his own books that trustworthy information can be obtained.
This story is open to grave suspicion, as, apart from the miracles recorded, there are wide discrepancies between the secular Portuguese histories and the narratives written or inspired by Jesuit chroniclers of the 17th century.
His graduation thesis, published in 1819, on the history of the Merovingian mayors of the palace, attracted the attention of Baron Stein, by whom he was engaged in 1820 to edit the Carolingian chroniclers for the newly-founded Historical Society of Germany.