Cyrodiil:Fighters Guild
The Fighter's Guild is a chartered organization regulating the hiring of mercenaries within the Empire. Historically, they've been present all over Tamriel, but the majority of their presence is in Cryodiil.
3rd Era
During the 3rd Era, the Fighter's Guild had a significant presence anywhere the Empire held sway.
During the time of the Nerevarine Prophecy in Morrowind, the Fighter's Guild was present in many Imperial colonies dotted around Morrowind. At the time, however, there was deep mistrust between the leader at the time, Sjoring Hard-Heart, and his predecessor, Percius Mercius, over the direction the Fighter's Guild was going. This culminated in the Nerevarine killing Sjoring at the request of Percius, and the Neverarine being named new Master of the Fighter's Guild in Vvardenfell.
During the Oblivion Crisis, the Fighter's Guild was in competition with the Blackwood Company, a rival mercenary group hailing from the Black Marsh. After the Champion of Cyrodiil discovered the Blackwood Company was using hist sap to send their mercenaries into a frenzy, an activity which led to them slaughtering an entire village, the Fighter's Guild destroyed the Blackwood Company, and the Champion of Cyrodiil became the Master of the Fighter's Guild.
4th Era
After the Great War between the Empire and the Aldmeri Dominion, the Fighter's Guild split into two factions: The Nibenese Branch, and the Colovian Branch. During the Great War, the Nibenese branch join the war against the Thalmor, while the Colovian branch refused. This difference in philosophy caused the two to separate, and the former to undergo strict reforms. The Nibense branch in Bruma is currently operating out of the old Fighter's Guild headquarters from the 3rd era. According to the leader of the Bruma branch of the Nibenese Fighter's Guild, Svenja Strong-Arm, they are led by two individuals known as Master Coltinius and Champion Cyrus.
While it is unknown who leads the Colovian Fighter's Guild, it is known that they are recruiting, although they don't currently have a headquarters in Bruma.
