Date of Event: March 2, Year 3019 T.A.

"'The Ents made up their minds rather quickly, after all, didn't they?' Pippin ventured....

'Quickly?' said Treebeard. 'Hoom! Yes, indeed.... I have not seen them roused like this for many an age. We Ents do not like being roused; and we never are roused unless it is clear to us that our trees and our lives are in great danger.... It is the orc-work, the wanton hewing — rárum — without even the bad excuse of feeding the fires, that has so angered us; and the treachery of a neighbour, who should have helped us.... There is no curse in Elvish, Entish, or the tongues of Men bad enough for such treachery. Down with Saruman!'

'Will you really break the doors of Isengard?' asked Merry.

'Ho, hm, well, we could, you know!... We can split stone like the roots of trees, only... far quicker, if our minds are roused! If we are not hewn down, or destroyed by fire or blast of sorcery, we could split Isengard into splinters and crack its walls into rubble.'...

Treebeard marched on.... But after a time his voice... fell silent again.... [His] old brow was wrinkled and knotted. At last he looked up, and Pippin could see a sad look in his eyes, sad but not unhappy. There was a light in them, as if the green flame had sunk deeper into the dark wells of his thought.

'Of course, it is likely enough, my friends,' he said slowly, '... that we are going to our doom: the last march of the Ents. But if we stayed at home and did nothing, doom would find us anyway, sooner or later. That thought has long been growing in our hearts; and that is why we are marching now. It was not a hasty resolve. Now at least the last march of the Ents may be worth a song. Aye,' he sighed, 'we may help the other peoples before we pass away.'...

The Ents... began to climb up... on to the high western ridge. The woods fell away and they came... to bare slopes where only a few gaunt pine-trees grew....

Pippin looked behind. The number of the Ents had grown — or what was happening? Where the dim bare slopes that they had crossed should lie, he thought he saw groves of trees. But they were moving! Could it be that the trees of Fangorn were awake, and the forest was rising, marching over the hills to war? He rubbed his eyes... but the great grey shapes moved steadily onward."

The Two Towers, LoTR Book 3, Ch 4, Treebeard