The O'Donnell dynasty entered 1557 in a state of dysfunction. Calvagh O'Donnell had imprisoned his own father, Manus O'Donnell, for two years - locked him up in order to seize the rule of Tirconnell, the lands roughly equivalent to modern County Donegal. Now, with John O'Neill marching from Tyrone with an army drawn from Armagh, Louth, and Monaghan, Calvagh found himself unsure what to do. He went to consult the man he had imprisoned. Manus, perhaps grateful that anyone was still listening to him or perhaps shrewd enough to set aside the grudge, gave clear-headed advice. Do not attack the O'Neills on their own ground, he said. Wait. Let them cross the river. Then strike their camp at Carraig Laith, where the Mourne and Finn meet to form the Foyle. The father knew what the son did not yet: timing wins battles.

John O'Neill had heard that Calvagh was hiding the cattle of Tirconnell in the wilds where they could not be plundered. He declared that even if Calvagh got past him with his animals, he would follow until the O'Donnells submitted to his authority. So the O'Neill army left its Tyrone camp, crossed the River Finn, marched through Raphoe and along the Laggan, and made a new camp at Baile-aighidh-chaoin - now known as Balleeghan townland, on the southern shore of Lough Swilly in Raymoghy Parish. Meanwhile, Calvagh was meeting with his commanders on the summit of Binnion - Bennin in the old form - a hill four kilometres northwest of Porthall and eight kilometres north of Lifford. With him stood his son Con, Walter McSweeney commanding two companies of gallowglass mercenaries from Fanad, and Donnell Gorm McSweeney with his own followers. The McSweeneys were professional warriors. They knew their business.

When the two scouts returned with the location of the O'Neill camp, Calvagh decided to abandon his father's advice. He would not wait. He would attack now. Two battalions descended on the camp at Baile-aighidh-chaoin, killing and slaughtering before O'Neill's men could form a defence. John O'Neill heard the commotion in his own camp, realized he was under attack, and slipped out the back of his tent. Two other men escaped with him: Hugh O'Donnell, son of Manus and Calvagh's own brother, who had inexplicably joined the O'Neill side; and Donough O'Gallagher, son of Felim Finn. The three men retreated toward Tyrone in the dark, on foot, with the rivers running high after heavy rain. They had to swim the Burn Deele, the River Finn, and the River Derg - all swollen, all dangerous. O'Neill made it as far as Tearmonn-Ui-Moain, bought a horse, and rode for Aireagal-da-Chiarog. He had survived. Many of his men had not.

By morning, Calvagh and his men were dividing the spoils. The haul was extraordinary. Con O'Donnell, Calvagh's son, received eighty horses as his portion. The prize of the lot was a single stallion, the personal mount of Shane O'Neill - John's son and one of the most formidable warlords of the era. The horse was called The Son of the Eagle, and chronicles record that the spoils of Binnion Hill were the richest of any battle between the O'Neills and the O'Donnells. For one night, Calvagh O'Donnell stood as Tirconnell's undisputed master. The success would not hold. Within years he would be captured by Shane O'Neill, his wife Catherine MacLean taken as well, the bitterness compounding. The Gaelic order itself had perhaps two generations left. But on Binnion Hill at dawn in 1557, with a stolen stallion grazing among the captured horses and the McSweeney gallowglasses laughing over the loot, the old Ulster was still alive.