Battle of the Umbra Hills

The Battle of the Umbra Hills was the final battle of the Scattered War. It took place around 500 PD, where the human rebels, led by a human warrior named Zan Tal'Dorei, and the elves on Syngorn fought against the human soldiers of the Kingdom of Drassig, led by King Trist Drassig, who allied themselves with demons to aid them. Ultimately, despite the excessive bloodshed that ended up cursing the Umbra Hills, where the battle took place, the Tal'Dorei killed Drassig and the rebels and elves were victorious.

Prelude
During the tyrannical reign of the Kingdom of Drassig by the necromancer King Neminar Drassig, a rebellion of men and elves continued to gain traction and bolster their ranks. One such individual was Zan Tal'Dorei, who proved herself a warrior and a leader by rallying the broken ranks of the resistance. They lured Drassig and his army to what they believed was the Syngornian outpost, the Shifting Keep, but that turned out to be an magical illusion that was dispelled and they were ambushed by the regrouped rebel forces, led by Tal'Dorei. The battle saw the death of King Neminar Drassig, spreading hope throughout the continent, but also cleared the way for his younger brother, Trist Drassig, to inherit the crown.

By the time that Trist Drassig claimed the throne for himself, the armies of the Kingdom of Drassig were stretched thin and people were turning against the crown throughout the lands. Lacking the brilliance and charisma of his predecessors, Drassig saw his armies slowly forced back as the rebel movement claimed victory after victory, eventually forcing the Kingdom's army back to their base in the Cliffkeep Mountains, north of Westruun.

The battle
After pushing the army back to the Cliffkeep Mountains, Zan Tal'Dorei led the rebels on a pursuit of Drassig and his soldiers to a valley in the Umbra Hills. There, they presumably caught up, and a battle broke out between the human rebels and the Elves of Syngorn against Drassig's soldiers and the fiends, devils that spawned from the Betrayer Gods, that the rebels discovered fought in their ranks. The battlefield was littered with the bodies and blood of men and demons alike, but it was finished when Zan Tal'Dorei killed Trist Drassig, marking the end of the battle and the Scattered War.

The Republic of Tal'Dorei
The abrupt end of the Drassig bloodline saw the Kingdom of Drassig all but collapsed. A council was formed by the leaders of the Verdant Expanse, who, seeing the people of the land accustomed to a singular leader, nominated the war hero Zan Tal'Dorei as their new ruler. Rejecting the title of king or queen, she wished to be referred to as Sovereign. Despite the protests of their new Sovereign, the council also voted to change the name of their continent after her, to "Tal'Dorei". Once power was divided equally among the council and the Sovereign, corruption and brutality was purged and peace was finally brought to the continent.

The Umbra Hills
The Umbra Hills was given its name after the battle. The grass and flowers that lived there grew black and burnt, and the sap of the plants native there now includes the blood of the demons that were killed during the battle.

Behind the scenes
The Battle of the Umbra Hills is described in the section of the same name in "Chapter 1: Campaigns in Tal'Dorei" of Critical Role: Tal'Dorei Campaign Setting, which was written by Matthew Mercer and James Haeck. The battle has, so far, not received any mention or reference on Critical Role.