Did you know these details about The Last March of the Ents, or the Battle of Isengard?
This event is actually one of Tolkien's clearest critiques of industrialization. In one of his letters, J.R.R. Tolkien spoke of his sadness at seeing the rural landscapes he loved as a child destroyed by factories and industrial development. As a result, many readers interpret the Ents' destruction of Isengard as nature's revenge against industry.
Tolkien also makes it clear that Saruman did not anger the Ents merely because he was their enemy, but because he systematically devastated Fangorn Forest. He specifically notes that Saruman cut down hundreds of trees to fuel his furnaces and forges. This is what led to Treebeard's famous words:
"There is no curse in Elvish, Entish, or the tongues of Men for this treachery."
In addition, Ents are naturally very slow to make decisions, with an Entmoot lasting for days. However, when they finally decided to attack Isengard, they did so knowing it would likely be their final act. Because the Entwives had been lost long ago, no new Entings could be born, meaning their species was already facing a slow extinction. Treebeard recognized that this great war might lead to their absolute end, which is why this tragic, final mobilization of their remaining strength is known as The Last March of the Ents.