The Voth used their art on commanders in your army to bend their will, learn of your plans, and make them betray you, Thorn continued.
Thorn knew the army would never betray their leader. 
mnli hypothesis: Thorn knew the army would never betray their leader.  premise: The Voth used their art on commanders in your army to bend their will, learn of your plans, and make them betray you, Thorn continued.