Hauser was a talented military officer who served as the commander of the Muse City army. Due to his capable command, he had been able to unite the armies of each city and stave off an invasion of the City-States of Jowston by the Highland Kingdom for some time prior to the outbreak of the Dunan Unification War.
He has served Muse City as a soldier since at least Solar calendar SY 446, when he was on hand to help Anabelle when she and Viktor investigated an arms merchant ring attempting to foster war between South Window City and Two River City.
As a soldier, Hauser held a very strict and disciplined attitude and made sure that all his actions as such were made on the basis of the law, refusing to fight as a military officer for any reason other than the law. He had a strong belief that the military should not wield political power and that the military acting on personal feelings invited chaos.
This is the reason why when Muse City fell to the Highland Army, he escaped the city with Jess and fought under him in his role as acting mayor of Muse, rather than joining the New Alliance Army, regardless of his personal confidence in Jess's decisions. It was only with the offical entry of Muse into the New Alliance Army in Tinto City that he would join the force.