Worse than this, he said, Perennis was plotting the Emperor's assassination and the elevation to the Principate of one of his two sons. This project of his, which he was furthering by astute secret machinations, had come to the knowledge of a loyal member of the Emperor's retinue. He had written of it to a brother of his, Centurion [Footnote: See Note D.] of the Thirteenth Legion, entitled "Victorious" and quartered on the Wall, along the northern frontier of Britain, towards the Caledonian Highlands. This letter had reached the quarters of the Thirteenth Legion late in September. Its recipient had at once communicated to his fellow-sergeants the horrible intimation which it contained. They had resolved to do all in their power to save their Prince by forestalling and foiling the treacherous Perennis. They had called a meeting of their garrison and disclosed their information to their men. The legionaries acclaimed their decision. Deputations set out east and west along the Wall and roused the other cohorts of the Thirteenth Legion and those of the Twenty-Seventh. From the Wall messengers galloped south to the garrisons throughout Britain. In an incredibly short time, despite the approach and onset of winter, they apprised every garrison in the island. Messengers from every garrison reached every garrison. So rapidly was mutual comprehension and unanimity established, so secretly did they operate, that on the Nones of January all the garrisons in Britain simultaneously mutinied, overpowered their unsuspecting officers, disclosed to them the reasons for their sedition, and invited them to join them. Of all the officers on the island only two hesitated to agree with their men. These, after some expostulation, were killed. The rest resumed their duties, if competent, or were relegated to civilian life, if adjudged incompetent.