Lugh was the son of Cian (son of Dian Cécht) and Ethne, making him the half Fomorian grandson of Balor. As a young child, the sea God Manannán mac Lir protected Lugh and took him away to safety from Fomorian rule. Whilst the Fomorians had seized three of the Great Treasures of the Children of Danu, Manannán protected the fourth, the Sword of Light. When the time was right he presented the sword to Lugh, along with a helmet that shone like the sun and a breast plate over his heart to return to battle the Fomorians.
Lugh arrives on his white horse, on three mighty waves to join the court of King Nuada. The doorkeeper will not let him in unless he has a skill with which to serve Nuada. He offers his many skills, but each time is rejected as the court already has someone with that skill. But when Lugh asks if they have anyone with all those skills, the doorkeeper lets Lugh join the court. After winning a flagstone-throwing contest against Ogma, the champion, Nuada wonders if Lugh lead them to freedom.
Meanwhile, Bres has returned with an army led by the Fomorian one-eyed giant Balor. On the Eve of Samhain (31 October in modern calendar) the second battle of Mag Tuired commences. At first, Lugh is kept away from the battlefield, but when Nuada is killed in battle by Balor, Lugh enters the battle his bright helmet blinding the enemy. Balor opens his evil eye that kills all it looks upon and Lugh throws the recovered Red Javelin Spear and drives his grandfather’s eye out the back of his head, causing panic among the Fomorian army who flee in terror.
Bres, alone and unprotected on the battlefield pleads for his life. Lugh spares his life on the condition that he teaches the Children of Danu how and when to plough, sow and reap.