Born in Livorno, Tuscany, Casula lived there until 1949 when, because of his father's death caused by an Allied bombardment of the city, his entire family moved to Cabras, Sardinia.
In 1969 he obtained the Libera Docenza in Paleography and Diplomatics, and started teaching History of Sardinia at the University of Sassari during that same year.
From 1985 to 1992 he has been cultural advisor to the President of the Italian Republic Francesco Cossiga,[1] and during those same years he took part in diplomatic missions in Romania, US, Spain and other countries.
He is the author of important works of notable scientific interest in Paleography and about the history of Sardinia, and during his years of historical research he has developed the so-called "doctrine of statehood", which revisits Sardinian history by denouncing the approximation with which, in his opinion, historians of the past, such as Zurita or Fara, have handed down the historical judgment on the events that took place on the Island;[3] he is considered one of the most important medievalists in Italy.
[1] During his long academic career he has been the author of numerous writings which, according to the list made by Francesco Floris,[4] make up a bibliography with 76 main titles: