At his fathers death in 1675 , his mother took over a regency in the name of her nine year old son and would remain in de facto power till 1684 when Victor Amadeus banished her further involvement in the state . At his father 's death in 1675 , his mother took over a regency in the name of her nine year old son and would remain in de facto power till 1684 when Victor Amadeus banished her further involvement in the state .