In the ecclesiastics who shared their banishment, the military exiles had a voluntary diplomatic _corps_ who lost no opportunity of advancing the common cause. At Rome, their chief agent was Father Luke Wadding, founder of Saint Isidore's, one of the most eminent theologians and scholars of his age. Through the friendship of Gregory XV. and Urban VIII., many Catholic princes became deeply interested in the religious wars which the Irish of the previous ages had so bravely waged, and which their descendants were now so anxious to renew. Cardinal Richelieu—who wielded a power greater than that of Kings—had favourably entertained a project of invasion submitted to him by the son of Hugh O'Neil, a chief who, while living, was naturally regarded by the exiles as their future leader.
To prepare the country for such an invasion (if the return of men to their own country can be called by that name), it was necessary to find an agent with talents for organization, and an undoubted title to credibility and confidence. This agent was fortunately found in the person of Rory or Roger O'Moore, the representative of the ancient chiefs of Leix, who had grown up at the Spanish Court as the friend and companion of the O'Neils. O'Moore was then in the prime of life, of handsome person, and most seductive manners; his knowledge of character was profound; his zeal for the Catholic cause, intense; his personal probity, honour, and courage, undoubted. The precise date of O'Moore's arrival in Ireland is not given in any of the cotemporary accounts, but he seems to have been resident in the country some time previous to his appearance in public life, as he is familiarly spoken of by his English cotemporaries as "Mr. Roger Moore of Ballynagh." During the Parliamentary session of 1640, he took lodgings in Dublin, where he succeeded in enlisting in his plans Conor Maguire, Lord Enniskillen, Philip O'Reilly, one of the members for the county of Cavan, Costelloe McMahon, and Thorlogh O'Neil, all persons of great influence in Ulster. During the ensuing assizes in the Northern Province he visited several country towns, where in the crowd of suitors and defendants he could, without attracting special notice, meet and converse with those he desired to gain over. On this tour he received the important accession of Sir Phelim O'Neil of Kinnaird, in Tyrone, Sir Con Magennis of Down, Colonel Hugh McMahon of Monaghan, and Dr. Heber McMahon, Administrator of Clogher. Sir Phelim O'Neil, the most considerable man of his name tolerated in Ulster, was looked upon as the greatest acquisition, and at his castle of Kinnaird his associates from the neighbouring counties, under a variety of pretexts, contrived frequently to meet. From Ulster, the indefatigable O'Moore carried the threads of the conspiracy into Connaught with equal success, finding both among the nobility and clergy many adherents. In Leinster, among the Anglo-Irish, he experienced the greatest timidity and indifference, but an unforeseen circumstance threw into his hands a powerful lever, to move that province. This was the permission granted by the King to the native regiments, embodied by Strafford, to enter into the Spanish service, if they so desired. His English Parliament made no demur to the arrangement, which would rid the island of some thousands of disciplined Catholics, but several of their officers, under the inspiration of O'Moore, kept their companies together, delaying their departure from month to month. Among these were Sir James Dillon, Colonel Plunkett, Colonel Byrne, and Captain Fox, who, with O'Moore, formed the first directing body of the Confederates in Leinster.