In 305 AD, the Romans had an advance fort set up to protect Roman Britain from the aggressive forces of the Picts. Amongst the soldiers was Decurion Sebastius Gralae. When his older brother claimed the family inheritance, Gralae had enlisted in the Roman Legion as a means of gaining the wealth and stature he would need to marry his beloved, Julia. When the communicator from a Nimon scout ended up in his possession, he negotiated a deal to sacrifice all the men in his fort in exchange for immortality. This would give him time to take the family inheritance from his brother. The Eighth Doctor stepped in to prevent the sacrifice of the fort's men, but couldn't stop a partial release of power — enough to make Gralae impervious to harm, and to keep him alive for centuries.