The Scarlet Guard is an organization of Hunters dedicated to the protection of Vale at all costs. Unlike an army, the Scarlet Guard doesn’t actually take orders from the Council of Vale, instead they act on their own initiative and take missions from the townspeople and the Council as they please. Otherwise their goal is to keep Vale and its surrounding areas safe from Grimm and others that would wish the city and its inhabitants harm.
A significant amount of the Scarlet Guard’s power comes from the nigh-supernatural powers they wield called Semblances, enabling members of the Guard to do everything from influence diplomatic decisions to win battles that are severely weighted against them. Nobody outside the Guard knows the true origin of these Semblances, but most citizens of Vale know of the incredible feats they enable.
There are rumors that certain members of the Guard operate as permanent spies for the upper echelon of Vale’s ruling structure, but these claims have never been substantiated.
Unbeknownst to a large portion of Remnant, the party discovered that the Scarlet Guard’s headquarters sustained an attack by an unknown party displaying incredible combat ability and ferocity. The attack resulted in every present member of the Scarlet Guard being killed, including it’s first-in command, Pyrrha Nikos.
It’s possible that the absence of the Scarlet Guard enabled the Shelling of Vale.