The Hadrian Wall, which stretches for seventy miles from the Solway Firth to the Tyne, nowhere touches Lancashire, but the frequent battles which raged in its vicinity were near enough to have an effect upon the district, and no doubt occasionally the invading forces from the North penetrated into the county. The Caledonians, in A.D. 180, broke through the wall, and for some time remained masters of a considerable portion of the North of England.[12] In A.D. 208 the Emperor Severus, with his sons Caracalla and Geta, visited Britain, and sent some of his soldiers to the North, as he found that the inhabitants of what is now Lancashire, Yorkshire and Cumberland had not yet become reconciled to the Roman government, and, to add to the difficulty, the people on the other side of the Hadrian Wall--the Picts and Scots--required repression. Severus died at York in 211, and for the next fifty years little is known of the Roman rule in Britain beyond the fact that the names of several legates, who acted as its governors, are on record. Between A.D. 258 and 282 the historians are also silent about this district, yet coins of Posthumus, Victorinus and Tetricus (three of the usurpers known as the "Thirty Tyrants") have been found in various parts of Northumbria which are now known as Lancashire. In A.D. 282 the Emperor Carus gave the island of Britain to his son Carinus, who was murdered in the year following. Passing over the next two Emperors, we find Carausius has the government of Britain ceded to him, and whilst on a visit to the Brigantes' district he was assassinated at York, A.D. 293, by his minister, Allectus, who at once usurped the purple in Britain; but not being acknowledged, a powerful force was sent against him from Rome, which met him not far from London, and in the engagement which followed he was slain and his army defeated. In the beginning of the next century, the Emperor Constantius Chlorus undertook an expedition against the Scots, and for that purpose appears to have made York his headquarters; he died in that city on July 25, A.D. 306, and his son Constantine was at once proclaimed Emperor by the garrison there stationed. The exact date of the introduction of the Christian religion into Lancashire is unknown, but we know that in 303 the Emperor Diocletian persecuted the followers of the new religion in Britain, and that the first recorded British martyr, St. Alban, died in 304 near the city which bears his name. Great must have been the change in the aspect of religious thought which, in 311, led to the conversion of Constantine the Great. This illustrious Emperor had no doubt a powerful influence over spiritual affairs in Lancashire, although the latter part of his life was not spent in Britain; he died in A.D. 337. The latter half of the century witnessed the beginning of the decline of the Roman power; the supposed unpassable Hadrian Wall was not enough to keep back the Northern warlike tribes, who, making their way through