Taken by white trees.
"I knew he was planning aught!" Handing back the messenger bird, the Shadow Knight trotted to his weapons and strapped them on quickly, prepared to claim his battle-witch no matter how deep into White Tree Sound he had to venture. A war with his neighbor wasn't in his plans, but he was known for his brutality and lack of predictability in battle.
If he was late to the battlefield with Green Dawn Cave, so be it. He valued the key to defeating the curse over arriving for battle on time.