Wulf was a young nobleman who dwelt in the western borderlands of Rohan. His father Freca attempted to force a marriage between Wulf and the daughter of King Helm Hammerhand. When Freca's plan failed, he was slain, and Wulf found himself declared the King's enemy. He fled across the borders into Dunland, where he seems to have been warmly received (it was said that Freca's family had a measure of Dunlendish blood). For four years, Wulf built up his power in Dunland, and allied himself with Rohan's enemies.
In the year Third Age 2758, with Rohan's armies drawn into the east to repel an attack there, Wulf and his allies invaded from the west. They overran the country and took Edoras, where Wulf sat in the Golden Hall and claimed the Kingship of Rohan. The true King, Helm, was driven into hiding in the mountains, and he died in the Long Winter that followed. In the spring, Helm was avenged by his nephew Fréaláf, who led a small party into Edoras and killed 'King' Wulf. With help from Gondor, Fréaláf cleared Wulf's followers from Rohan, and succeeded his uncle Helm to become its tenth rightful King.