| Sorry. I'll send you a refund.
As a mercenary leader who fought for his livelihood, Gilbert happened to be in the Highland Kingdom when he was hired by the Highland Army. During the Dunan Unification War, he participated in the first assault on Muse City but was convinced to switch sides mid-battle by Flik and Viktor, who had met Gilbert when he was hired by Muse in the past. Following the battle, Gilbert continued to serve with the New State Army through the Dunan Unification War as an infantry captain.
While betraying a contract is a poor action for a mercenary, following someone like Luca Blight who would slaughter women and children without thought was a pretty unconscionable thought to most. Gilbert especially felt that doing so, when he had left his wife, Mary and son, Thomas behind in Zexen to pursue employment in the first place, would be an unforgiveable act.
Following the end of the war and sick of fighting, he returned to his family in Zexen where he was able to put his heart to rest.