The Irish rally may be dated from the year 1241. In that year Maeleachlainn O'Domhnaill became king of Tir Conaill, and by his aid Brian O'Neill became king of Tir Eoghain, defeating in battle the last king of the MagLochlainn line, one who was favourable to the Foreigners and no doubt acknowledged the dominion of the Earl of Ulster. The viceroy, or, as he was then called, justiciar, of the English king as lord of Ireland, was Maurice FitzGerald. He was the most active and enterprising of the new rulers since the first generation of bold adventurers had passed away, and he set himself the task of completing the conquest of Ireland by making the Earl de Burgh effective ruler of his titular lordships of Connacht and Ulster. In Connacht, he succeeded so far as to make the king of Connacht, Feidhlimidh O'Connor, his subject ally, allowing him to retain the title of king. In 1242, FitzGerald took the first step towards the reduction of Ulster by leading an army from Connacht against Tir Conaill and compelling the king, Maeleachlainn O'Domhnaill, to give him hostages. As yet, no fresh occupation of Ulster territory was attempted.

From the earliest times until the Confiscation of Ulster, the southern frontier of that province made invasion difficult. It was protected by broad lakes and rivers and deep woods, and probably also by the remains of that great ancient line of earthworks of which I have spoken in an earlier lecture. When Ulster was invaded by land, the approach was almost always on the eastern side from Dundalk or Ardee towards Armagh, or on the western side between Lower Loch Erne and the sea-coast. Maurice FitzGerald planned to invade it, building castles as he gained ground, both on east and west. In 1244 we read of a new castle built at Donaghmoyne, near Carrickmacross.

Next year, 1245, FitzGerald was summoned by Henry III. to aid him in an invasion of Wales. He went across with an Irish army and his subject king of Connacht. The enterprise did not answer expectation, and Henry sent FitzGerald back deprived of the viceroyship. FitzGerald nevertheless resumed his plan of conquest, the new viceroy, FitzGeoffroi, seconding him. In 1247 he built a castle at Sligo, as a basis of operations towards the Erne. This done, the next step was to seize and fortify the passage of the Erne at Ballyshannon; but he found the king of Tir Conaill there on guard. FitzGerald ordered his Connacht auxiliaries to pretend a retirement and to make a circuit crossing the Erne some miles further up. The stratagem succeeded. The king of Tir Conaill, attacked in front and flank, was defeated and fell in the fight. At his side fell a chief named MacSomhairlidh, "the son of Sumarlidi." This name is the first sign of the Hebridean Galloglach element in Irish wars.

Next year, 1248, the justiciar FitzGeoffroi cooperated in the campaign against Ulster. He led an army to Coleraine, where already there was a castle on the eastern side of the Bann. He built a bridge and built a second castle on the western side, thus securing a new way for invasion. Brian O'Neill did not remain inactive. He brought ships over land from Loch Foyle to Loch Erne, and attacked and demolished a castle at Belleek, newly built by FitzGerald. Fast upon this followed a revolt of Feidhlimidh O'Connor. The viceroy marched to FitzGerald's aid and Feidhlimidh was driven out, but returned next year and continued to hold his own.

In 1250, taking advantage of a dispute about the succession, FitzGerald invaded Tir Conaill but did not remain there. In 1252, he renewed the attack, building a new castle near Belleek and another on the eastern frontier near Banbridge. The viceroy also came on with a strong army, penetrating into Tir Eoghain by way of Armagh. O'Neill bent before the storm and made submission. This was the culminating point. Next year, 1253, hoping to enforce his advantage, the viceroy once more invaded Tir Eoghain, but this time he obtained no submission and was forced to retreat with heavy loss. O'Neill forthwith took the offensive, invaded the Earl of Ulster's territory, and destroyed a number of castles including the new castle near Banbridge. There is a lull at the turning of the tide. For several years, hostilities cease on both sides. Then in 1257, Godfrey O'Domhnaill, king of Tír Conaill, destroys again the castle of Caoluisce near Belleek and attacks Sligo, burning the town. Retiring, he fights a rearguard action, and both he and Maurice FitzGerald receive wounds of which they afterwards die.

Under the following year, 1258, is chronicled an event in itself of the greatest significance and also an index of the significance of foregoing events. Of the unsubdued Irish outside of Ulster, the chief potentates at this time were Tadhg O'Briain, king of Thomond, and Aodh O'Connor, king of Connacht, son of Feidhlimidh who had cast off the authority of FitzGerald and De Burgh. These two kings assembled their nobles and their forces and marched together to Caoluisce on the Erne, the site of the demolished fort. They met there Brian O'Neill, king of Tyrone, "and," says the annalist, "all those nobles gave the supreme authority to Brian O'Neill." That is to say, so far as lay in their power, by a spontaneous act, they restored the monarchy of Ireland.

Therefore, when I say that Brian O'Neill's defence of Ulster, with the co-operation of the kings of Tir Conaill, marks the definite rallying point against the Norman conquest, I give something more than a private opinion or a modern inference. It is a fact to which, in the year 1258 on the banks of the Erne, the kings and nobles and fighting men of Thomond and Connacht, as well as of Tyrone, render the clearest and most solemn testimony possible. Never before in Irish history had the chief provincial kings thus spontaneously and peacefully awarded the high-kingship to one of their number. The act implied a repudiation of the authority that set up feudal lords over Irish kings, and amounted to a declaration of national independence. Half a century later, Brian O'Neill's son, in a letter to the Pope, again declares the Plantagenet lordship of Ireland to be null and void and asserts the right of the Irish to determine their own sovereignty.

These facts prove that the first factor in the Irish rally of the thirteenth century was the sense of nationality, intensified by adversity. Of this we shall see new and striking proofs.

About this time, the Irish began to strengthen their domestic polity by adopting the custom of tanistry.