Editing Fergus mac Róich (section)

==Táin Bó Cúailnge==
When Ailill and Medb raise a huge army and launch the ''[[Táin Bó Cúailnge]]'' (Cattle Raid of [[Cooley peninsula|Cooley]]) to steal Ulster's stud bull, [[Donn Cúailnge]], Fergus' knowledge of the terrain means he is chosen to lead the way. He leads the army by a roundabout route, hoping to give the Ulstermen time to raise their own army, but they are disabled by a curse. He sends a message to Cúchulainn, who begins his single-handed defence of the province.

The Connacht army separates, with Ailill leading one section, and Medb and Fergus leading the other. Ailill is suspicious, and sends his charioteer to spy on them. The charioteer finds Fergus and Medb having sex, and unnoticed, steals Fergus' sword, which Ailill keeps safe as proof. Fergus makes himself a dummy sword of wood to hide his loss. Cúchulainn holds up the army's progress by fighting a series of champions in single combat. Fergus is sent to face him, but as foster-father and foster-son, neither wants to fight the other, and in any case Fergus has no sword. Cúchulainn agrees to yield on this occasion, on the condition that Fergus yields the next time they meet.

Eventually the Ulstermen recover from their curse, and the final battle begins. Ailill gives Fergus back his sword. Fergus meets Conchobar on the battlefield, and has him at his mercy, but is prevented from killing him by Cormac. He redirects his rage into cutting off the tops of three hills with his sword. Cúchulainn, who has so far sat out the battle, recuperating from his wounds, enters the fray and challenges Fergus. Fergus honours his promise and yields, pulling his followers from the field. Medb's other allies, seeing him withdraw, panic and begin to retreat. The Connacht army is routed, and Fergus bitterly remarks, "It is the usual thing for a herd led by a mare to be strayed and destroyed."<ref>[[Thomas Kinsella]] (trans.), ''The Táin'', 1969</ref>