Sauron Approaches Tol-in-Gaurhoth, the Isle of Werewolves

"Tol-in-Gaurhoth was held by Orodreth, however, Orodreth was powerless to stop Sauron from taking the isle, and fled south.

Sauron began breeding large wolves in the isle, and, by sending evil spirits into the fell beasts, turned them into werewolves.

Ten years later, during the Quest for the Silmaril, Beren Erchamion enlisted Finrod's aid, but they were captured while passing the isle.

Sauron defeated Finrod in a contest of spells and songs, and their companions were slain by werewolves. Finrod saved Beren's life, but in doing so, he died himself.

Lúthien and Huan, Hound of Valinor, came to Beren's rescue, and Huan killed the wolves sent against him. After Draugluin was killed, Sauron went out in wolf-form but was defeated.

Lúthien gained control over the isle from Sauron, who fled, and, after releasing those who had been captive there under Sauron, she reduced the castle to ruins. Finrod was buried there by Beren and Lúthien." Courtesy of Tolkien Gateway