How Ireland was won, lost, and won again — six times over
Before Ireland belonged to anyone, it had to be fought for. The Book of Invasions — the Lebor Gabála Érenn in Irish — is the great mythological history of Ireland, the story of six waves of people who came to the island, one after another, and how each of them won or lost it. It is part history, part mythology, and entirely extraordinary, written down by Irish monks in the 11th and 12th centuries but drawing on stories that had been told for centuries before that.
Think of it as Ireland’s creation story — except that instead of gods making the world in seven days, Ireland is shaped by invasion after invasion, each new people building on the ruins of the last. By the time the story is finished, Ireland has been transformed from a wild empty island into the home of the Irish people.
The First People: Cessair
The very first person to set foot in Ireland — according to the Book of Invasions — was a woman named Cessair, the granddaughter of Noah. She arrived with a small group of followers just before the great biblical flood, hoping that an island at the edge of the world might escape the rising waters. It did not. The flood came, and everyone in Cessair’s company drowned — except for one man named Fintan mac Bóchra, who escaped by transforming into a salmon and swimming away. Fintan lived through all the ages of Ireland, changing shape again and again, and eventually became the witness whose memories made the Book of Invasions possible.
The Second Wave: Partholón
Three hundred years after the flood, a man named Partholón arrived from the east with his people and began the real work of making Ireland habitable. They cleared the forests, created the plains, dug the lakes, and built the first houses. They fought Ireland’s first great enemy — the Fomorians, the dark supernatural beings who had claimed the island as their own. Partholón’s people won that fight, but they could not win against plague. Every single one of them died of sickness in a single week, leaving Ireland empty again.
The Third Wave: The Nemedians
Next came the Nemedians — the people of Nemed — who arrived to find Ireland deserted and made it their home. Like Partholón’s people, they fought the Fomorians and struggled to survive. The Fomorians demanded a terrible tribute: two thirds of the Nemedians’ children, their grain, and their milk every year on the night of Samhain. The Nemedians eventually rebelled and attacked the Fomorian stronghold on Tory Island — and lost catastrophically. The survivors scattered to the four corners of the world, but their descendants would return.
The Fourth Wave: The Fir Bolg
Some of the scattered Nemedians ended up in Greece, where they were enslaved and forced to carry bags of soil for their masters. Eventually they built boats out of those leather bags and sailed back to Ireland, landing as the Fir Bolg — “the men of the bags.” They divided Ireland into five provinces — Ulster, Munster, Leinster, Connacht, and Meath — a division the country still uses today. The last Eochaid mac Eirc, was said to be so just that no rain fell during his reign except as dew, and no year passed without harvest.
The Fifth Wave: The Tuatha Dé Danann
Then came the Tuatha Dé Danann — the gods of Ireland. They arrived in a cloud of mist, or in some versions by burning their ships so they could not retreat, and they brought with them four great treasures from four magical cities: the Stone of Destiny, the Spear of Lugh, the Sword of Nuada, and the Cauldron of the Dagda. They defeated the Fir Bolg at the First Battle of Mag Tuired and then drove the Fomorians from Ireland forever at the Second Battle of Mag Tuired. For a golden age, the gods ruled Ireland.
The Sixth Wave: The Milesians
But even the gods couldn’t hold Ireland forever. The final invasion came from the sons of Míl Espáine — the Milesians, the ancestors of the Irish people. Their poet Amergin composed a great song as he set foot on Irish soil, claiming the island with his words. The Tuatha Dé Danann tried to drive the Milesians back with a magical storm, but Amergin calmed it with his poetry, and the Milesians landed and fought. The gods were defeated — and rather than vanish entirely, they made a deal. Ireland would be divided: the Milesians would have the world above ground, and the Tuatha Dé Danann would take the world beneath, retreating into the fairy mounds that are still scattered across the Irish landscape today.
Key facts about The Book of Invasions
- Irish title: Lebor Gabála Érenn (“The Book of the Taking of Ireland”)
- Number of invasions: Six — Cessair, Partholón, Nemedians, Fir Bolg, Tuatha Dé Danann, Milesians
- Written down: 11th–12th century manuscripts; based on much older oral tradition
- Key witness: Fintan mac Bóchra — transformed into a salmon to survive the Flood; remembered everything
- Five provinces: Created by the Fir Bolg — Ulster, Munster, Leinster, Connacht, Meath
- Four treasures: Stone of Destiny, Spear of Lugh, Sword of Nuada, Cauldron of the Dagda
- Final outcome: Milesians take Ireland above ground; Tuatha Dé Danann retreat into the fairy mounds
- Cycle: Mythological Cycle
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