When Brithwyn split from Calaria, it swore off the influence of outside organizations and chose instead to rule from within. The sole exception to that declaration is Protectorate.
A Brith Org from the start, Protectorate is a private army-for-hire. Before the countries had split, Protectorate was the company to hire when you had a government to destabilize or a war to wage. While the Calarian army was reserved for crusades and the like, Protectorate went to the highest bidder. When Brithwyn looked to break itself from its Calarian chains, Protectorate soldiers helped it free its bonds.
The Protectorate now generally acts as peacekeepers within Brithwyn, but they're still available for use in any conflict of one's choosing for the right price. The gems of the Protectorate army are their slayers: elite soldiers who've trained until they can enter a powerful "battletrance." Stories of entranced slayers singlehandedly tearing through rival encampments are familiar amongst mercenaries -- and it's believed that they're only slightly exaggerated.