The Monarchia Lusytana, written by the monks of Alcobaça between 1597 and 1729, is an assumedly religious work that adopts a chronistic nature by recounting the history of the kingdom of Portugal from the formation of the Condado Portucalense to the beginning of the reign of King João I. As I am developing research in the field of the historiography of the Military Orders, it seemed appropriate to delve into the theme of the Crusades and the Military Orders in the Monarchia Lusytana, a work from the scriptorium of the monastery of Alcobaça, with a long tradition of documentary and codicological production. The aim of this work is to ascertain how the Military Orders and the Crusade are approached and what impact they had on the history of Portugal.