The tree-like race that marches on Isengard in J.R.R. Tolkien’s The Lord of the Rings is the Ents. They are ancient shepherds of trees who protect the forests and are led by Treebeard, also called Fangorn.
Merry and Pippin meet Treebeard after being captured by Orcs and brought into Fangorn Forest. Their account of Saruman’s destruction of trees helps persuade him that the Ents must take action. The Ents gather at an Entmoot, a deliberative meeting, and decide to attack Isengard.
Their assault destroys Saruman’s industrial stronghold and breaks the dam, flooding the surrounding works. Tolkien distinguishes Ents from Huorns, another mysterious tree-associated group, although the boundary between the two is not always sharply defined. The Ents’ role also reflects Tolkien’s recurring concern with environmental destruction and unchecked industrialization.