O’Cahan, who was charged with complicity in O’Dogherty’s outbreak, or with being at least a sympathiser, had been arrested, and was kept, with Nial Garve, a close prisoner in Dublin Castle. An anonymous pamphleteer celebrated the victories that had been achieved by the lord deputy, giving to his work the title, ’The Overthrow of an Irish Rebel,’ having for its frontispiece a tower with portcullis, and the O’Dogherty’s head impaled in the central embrazure. The spirit of the narrative may be inferred from the following passage: ’As for Tyrone and Co., or Tyrconnel, they are already fled from their coverts, and I hope they will never return; and for other false hearts, the chief of note is O’Cahan, Sir Nial Garve, and his two brothers, with others of their condition. They have holes provided for them in the castle of Dublin, where I hope they are safe enough from breeding any cubs to disquiet and prey upon the flock of honest subjects.’
O’Cahan and his companion, however, tried to get out of the hole, although the lord deputy kept twenty men every night to guard the castle, in addition to the ordinary ward, and two or three of the guards lay in the same rooms with the prisoners. Their horses had arrived in town, and all things were in readiness. But their escape was hindered by the fact that Shane O’Carolan, who had been acquitted of three indictments, cast himself out of a window at the top of the castle by the help of his mantle, which broke before he was half way down; and though he was presently discovered, yet he escaped about supper time. ‘Surely,’ exclaimed the lord deputy, ’these men do go beyond all nations in the world for desperate escapes!’ The prisoners were subsequently conveyed to the Tower, where they remained many years closely confined, and where they ended their days. Sir Allen Apsley, in 1623, made a report of the prisoners then in his custody, in which he said, ’There is here Sir Nial Garve O’Donel, a man that was a good subject during the late queen’s time, and did as great service to the state as any man of his nation. He has been a prisoner here about thirteen years. His offence is known specially to the Lord Chichester. Naghtan, his son, was taken from Oxford and committed with his father. I never heard any offence he did.’