Religion was the most important element that united the Gaelic Irish and the old Anglo-Irish aristocracy. While the Catholic fath was under severe military, legal and economic pressure in Ireland, communication was maintained between the exiled Gaelic chieftains, the Irish monasteries on the Continent and the various international religious orders.
Sons of the chiefs who left Ireland in 1607 either joined various continental armies or studied for the priesthood in seminaries as far away as Prague and Salamanca.
Church annalists in Ireland had always been diligent in keeping exact records of events of importance - battles, marriages, successions of kings and chieftains, deaths of abbots and poets, as well as the traditions and language of Ireland. Recording the history of the country, as was done in such works as the Annals of the Four Masters, was an important part of the Counter Reformation in Ireland.