Mag Lena

Mag Lena — also written Mag Léna or Mag Léne — was a plain in the ancient territory of Firceall, lying between modern Tullamore and Durrow in County Offaly. It straddled the Esker Riada, the great ridge of glacial gravel that formed Ireland's principal east-west highway and the traditional boundary between the northern and southern halves of the island. The dindshenchas, Ireland's medieval lore of place-names, derives 'Lena' from a son of the hospitaller Mac Da Thó, said to have been buried on the plain.

The plain's central place in Irish legendary history comes from the Battle of Mag Lena, fought, by tradition, in the second century AD between Conn Cétchathach — Conn of the Hundred Battles — and Eógan Mór, also called Mug Nuadat. The battle ended with Ireland divided along the line of the Esker Riada into two halves: Leath Cuinn, 'Conn's Half', in the north, and Leath Mogha, 'Mug's Half', in the south. This division remained a fundamental way of describing Ireland's geography and politics for centuries afterward, and the medieval account of the battle was translated and published by the scholar Eugene O'Curry in 1855.

Mag Lena's role as a contested crossing-point did not end with legend. The plain hosted a real synod around 630 AD, called to settle the controversy over the correct dating of Easter, a battle in 906 AD involving Cormac mac Cuilennáin, the celebrated king-bishop of Munster, and a further conflict in 1090 AD during a struggle over the High Kingship — a thousand years of history layered onto a single stretch of Offaly heath.