Battle of Tyllan
The battle was a defeat for the Imperial forces, composed mostly of men from Elstreth, which were wiped out in a pincer movement by the Horned Cabal. The Horned Cabal victory left the Aldoran capital defenseless to the undead host. The Horned Cabal's move towards Elstreth took them through the Gattrof Mountains and the pass at Skyreach. This lead to the Battle of Skyreach.
The Order of Voln is known to intone "Remember Tyllan, remember Skyreach!" to galvanize its forces in battle.