Ireland was ruled for thirty-seven years by the Fir Bolg, and they prospered. One night, however, their king Eochaidh Mac Eirc had a dream in which he saw a great flock of birds coming from the ocean, and his poet explained to him that this was a fleet of ships carrying a thousand magical heroes. Soon such a fleet arrived, and the warriors came ashore, burned their ships, and encamped on a mountain in Connacht. The Fir Bolg sent the greatest of their own warriors, called Sreang, to parley with them, and the strangers said that they were relatives of theirs, called Tuatha Dé Danann. They had come from the northern world, and their king was Nuadhu. They proposed that Ireland should be shared by the two peoples, but the assembly of the Fir Bolg at Tara refused this. The result was a great battle fought at Maigh Tuireadh (‘the plain of the pillars’) near Cong in County Mayo. King Eochaidh of the Fir Bolg was slain, but Sreang with a sword-stroke severed the right arm of Nuadhu. The tide of battle went against the Fir Bolg, and Nuadhu agreed a treaty with Sreang which allowed the west of Ireland to the Fir Bolg, while the Tuatha Dé took the rest.
The Tuatha Dé were a magnificent people, with skilled artists and tradesmen, and many wizards to plan their future for them. However, it was not long before they were troubled by a group of pirates called the Fomhóire, who commenced raiding the country. Since Nuadhu was blemished, it was considered unlucky for him to rule, and the Tuatha Dé sought to achieve harmony with the Fomhóire by appointing as their ruler Breas, a warrior whose father was of the Fomhóire and whose mother was of the Tuatha Dé. After seven years in power, Breas proved himself so selfish and high-handed that the people were alienated from him. Moreover, the Fomhóire began to impose heavy taxes and, groaning under the oppression, the Tuatha Dé decided to rebel. They deposed Breas, and in retaliation the Fomhóire sent a huge fleet of ships to attack Ireland, led by their fierce chief Balar, who had an evil eye in his forehead. This eye destroyed all on which it looked.
The great physician of the Tuatha Dé, Dian Céacht replaced Nuadhu’s severed limb with a mobile silver arm, and Nuadhu reassumed the kingship. He held a great assembly and banquet at Tara, at which preparations were made for the inevitable trial of strength with the Fomhóire. During the proceedings, a handsome young stranger arrived and demanded entry. This was Lugh, whose father Cian was of the Tuatha Dé but whose mother Eithne was a daughter of Balar. Lugh was admitted because he was the master of all arts and, impressed by his stupendous skills, Nuadhu decided to make him commander of the forces for thirteen days. Lugh then delegated functions to the warriors, and to all the various craftsmen and magicians. For his part, the old father-figure of the Tuatha Dé, called ‘the Daghdha’, enlisted the help of the magical mother-goddess, the Mór-Ríoghain, and then went to the Fomhóire camp to try to forestall hostilities, but he was mocked and humiliated there.
Again the battle-site was a place called Maigh Tuireadh, but this was the great rock-filled plain east of Lough Arrow in County Leitrim. The two strong armies advanced across the plain and met each other with a frightful shock. There was a great tumult of banging shields and of shouting men, and the slaughter was atrocious on both sides. In the hand-to-hand fighting, warriors were tripping over bodies and slipping and falling in the torrent of blood. Shoving aside his bodyguards, Lugh rushed to the forefront of the Tuatha Dé, and began to dance in a circle on one leg, while he chanted a magical spell. The special cover was being removed from the eye of Balar, and that tyrant was ready to turn his withering glance on the Tuatha Dé. Lugh immediately threw a stone from his sling and drove the eye to the back of Balar’s head, so that it was looking on the Fomhóire host. The Fomhóire were weakened, and they took to flight towards the sea.
The Daghdha recovered all the cattle which the Fomhóire had seized as tribute in Ireland, and the Mór-Ríoghain announced the great victory on hill-tops in all parts of the country.