War of the black yew (glossary)
The War of the Black Yew was a massive conflict that engulfed the Reach in the Chaos of the Seventh Century, a culmination of decades of warfare between the powers of the wood and their servants and the realms of the Etrandexi and Aversaria. It was ignited by the return of Carttuen Silver-Hair, who sought to enact the ritual known as the I-Amanthil, which would've merged the realms of the mundane and those of Dream, finally returning the land of the fey to what she perceived to be its rightful masters.
Carttuen would ultimately be defeated by a vast coalition of local Etrandexi, Aversarians, Clanlanders and even dissenting fey, and the conclusion of the war would result in the establishment of the Truce of the Hearth and Wood, which finally delineated the boundaries of the old powers and the realms of man, putting an end to fifty years of bloodshed and ending large-scale conflict between the two sides for good.