A. 1.--After the death of Severus in A.D. 211, Roman historians tell us nothing more concerning Britain till we come to the rise of the only other Emperor who died at York, Constantius Chlorus. During the miserable period which the wickedness of Caracalla brought upon the Roman world, when Pretender after Pretender flits across the scene, most to fail, some for a moment to succeed, but all alike to end their brief course in blood, our island remained fairly quiet. The Army of Britain made one or two futile pronunciamentos (the least unsuccessful being those for Postumus in A.D. 258, and Victorinus in A.D. 265), and in 277 the Emperor Probus, probably to keep it in check, leavened it with a large force recruited from amongst his Vandal prisoners,[316] whose name may, perhaps, still survive in Vandlebury Camp, on the Gog-Magog[317] Hills, near Cambridge. But not till the energy and genius of Diocletian began to bring back to order the chaos into which the Roman world had fallen does Britain play any real part in the higher politics. A. 2.--Then, however, we suddenly find ourselves confronted with names destined to exert a supreme influence on the future of our land. The Saxons from the Elbe, and the Franks from the Rhine had already begun their pirate raids along the coasts to the westwards.[318] Each tribe derived its name from its peculiar national weapon (the Franks from their throwing-axe (_franca_),[319] the Saxons from the _saexes_, long murderous knives, snouted like a Norwegian knife of the present day, which they used with such deadly effect);[320] and their appearance constituted a new and fearful danger to the Roman Empire. Never, since the Mediterranean pirates were crushed by Pompey (B.C. 66) had it been exposed to attacks by sea. A special effort was needed to meet this new situation, and we find, accordingly, a new officer now added to the Imperial muster,--the Count of the Saxon Shore. His jurisdiction extended over the northern coast of Gaul and the southern and eastern shores of Britain, the head-quarters of his fleet being at Boulogne. A. 3.--The first man to be placed in this position was Carausius,[321] a Frisian adventurer of low birth, but great military reputation, to which unfortunately he proved unequal. When his command was not followed by the looked-for putting-down of the pirate raiders, he was suspected, probably with truth, of a secret understanding with them. The Government accordingly sent down orders for his execution, to which he replied (A.D. 286) by open rebellion, took the pirate fleets into his pay, and having thus got the undisputed command of the sea, succeeded in maintaining himself as Emperor in Britain for the rest of his life.