Treebeard, also known as Fangorn, was an Ent. He was the most ancient of all Ents and was their leader. Merry and Pippin encountered him in Fangorn Forest when he saved them from Grishnákh. After a 3-day long Entmoot (gathering of Ents), he and the other Ents decided to attack the traitor Saruman at Isengard. The Ents attacked Isengard and destroyed the dam of the river Isen, flooding Isengard and destroying all of Saruman's war machines and forges. Although they flooded the ring of Isengard, they were unable to destroy or even damage the tower of Orthanc, leaving Saruman locked in his tower.