Brennos was the leader of the army of Celtic tribes in 279 BC. His army defeated Callippus of Athens at Thermopylae and subsequently sacked the city of Delphi and burned the Temple of the Pythia. That night, he was found in a pool of his own blood, his throat cut. His men blamed his co-commander Acichorios, leading to a chain of events that would secure the stability of the Eighth Earth Front.
In the 20th year of the War in Heaven, Robert Scarratt tried convincing Brennos of the historical necessity of his suicide, but after considering the idea of killing him himself, he gave up in frustration; he left thirty minutes before Brennos' historical death in case a later Great Houses agent would need to return and finish the job.