It began with a boy named Cuhulain, the protagonist of the story, who was the son of a god but also part mortal. He gained his father's "god like" strength which helped him throughout his life.
The Ulster Cycle also focuses on the Warriors of the Red Branch. It chronicles the Cattle Raid of Cooley which began the Battles.
There was betrayal among the Ulster men because of Dierdre, a beautiful maiden who was claimed by the King Conner Mac Nessa. Dierdre fell in love with Narius, an Ulsterman, and that is when the seperation began. The trama was the catalyst to a war between two rival countries, Ulster and Connaught.
A long time curse, known as the "pangs" prohibits the Ulstermen from moving when the war begans. Because Cuhulain was part god the "pangs" didn't affect him and he had to fight the war alone.
He died by the sword of and enemy.