The Von Matternich family was one of the few families that had sided with the ruling royal family, the Van Rechteren family during the 'Great Unification'. In the constant wars with the south over the hegemony of the North, many noble families had sided with the South who had been deemed as the obvious victor of the Great Unification.
The war, expected to be a sweeping victory for the South, ended up becoming a humiliating slog for roughly three decades. Millions were killed on the battlefields, with the newly-forming Federation on the west joining to help the Matternich. Slowly but surely, the South lost their footing, and had to sue for peace.