Gregorian Reform
In the "Annales", he treats history in strict chronological order and keeps theology in the background. Lord Acton called it "the greatest history of the Church ever written". In the "Annales", Baronius coined the term "Dark Age" in the Latin form "saeculum obscurum", to refer to the period between the end of the Carolingian Empire in 888 and the first inklings of the Gregorian Reform under Pope Clement II in 1046.