Hugh Ruadh O’Donnell had been over four years eating out his heart in prison in Dublin Castle. He was a man grown now, twenty years of age, and he longed for freedom and revenge. ‘ On Christmas night, 1591, ” it seemed to the Son of the Virgin full time that he should escape,” and he and his fellow-prisoner, Art O’Neill, son of Shane, let themselves down by a rope from a window of the Castle. Outside, a servant had been awaiting them, and they passed unobserved through the streets. Once in the open country, Hugh, Art and the servant pushed on to the mountains, toiling along in the sleet and snow, which soaked their thin garments. Art soon was so exhausted that he had to lean on the shoulders of the other two.

At length both the young men were worn out, and they took shelter under a rock, while the servant hurried to Glenmalure, to ask Fiach Mac Hugh O Byrne, the chief who ruled there, to send assistance. A rescue party was at once despatched, but when it reached the rock Art and Hugh were found lying ” like sods of earth covered up with snow.” Art was beyond help, but Hugh they finally succeeded in reviving, and then they bore he was nursed back to health. Hugh O’Nsill was not long in hearing of his young brother-in-law’s escape.

Had O’Neill been a mere Celtic chief, whose political aims went no further than the aggrandizement of his own clan, this news would have afforded him little satisfaction. For generations there had been strife and jealousy between the chiefs of Tir Owen and Tirconnell. But the present head of the Ui Niall was a politician of wider views. He saw that a united Ulster must be the first step towards the united Ireland of which he dreamt. He sent a message to Hugh Ruadh, asking him to come at once to him, and Hugh Ruadh came.

They remained some days together, and when O’Donnell returned to Ballyshannon to his parents, no doubt the plan of the future insurrection had been already sketched and agreed on. Soon after, his father having resigned the chieftaincy, the men of Tfrconnell inaugurated Hugh Ruadh at Kilmacrennan with all the ancient rites (1592).