The Second Battle of Mag Tuired (Cath Maighe Tuireadh)

The battle the whole Mythological Cycle turns on: the Tuatha Dé against the Fomorians, with every god in it.

This is the central event of the Mythological Cycle and the one that ties the separate gods together into a single story.

It begins with bad government. Nuadha had lost his arm and so his kingship, and Bres had taken it. Bres was half Fomorian, and under him the Tuatha Dé were taxed to the bone and set to menial work, their poets insulted, their champions carrying firewood. When he was finally put out he went to his father's people for an army.

Lugh arrived at Tara in the middle of the preparations, was admitted for being skilled in everything at once, and was given command. What follows is a roll call of what each god will do. The Dagda will fight with his club. Goibniu the smith will repair every broken weapon overnight, and any spear he makes will not miss. Dian Cécht will put the dead in a well of healing and they will rise the next morning. Ogma will clear the field.

The Fomorians answer by sending Ruadán, Bres's own son by a woman of the Tuatha Dé, to kill Goibniu at the forge. Ruadán fails and dies, and his mother Brigid comes to the field and keens over him, which the tradition gives as the first keening ever heard in Ireland.

Nuadha is killed by Balor. Lugh kills Balor. The Fomorians break. Bres is captured and spared, on the condition that he tells the Tuatha Dé when to plough, when to sow and when to reap, which is the price of his life and the end of the war.