Severus’s last war was in Britain; he drew a Wall of thirty-two miles from sea to sea. Paulus Orosius, who wrote A.D. 417, says, that the conqueror Severus— Having fought many severe battles, determined to separate the part of the island which he had recovered, from the tribes that remained unsubdued, and, therefore, drew a deep fosse, and a very strong Vallum (_magnam fossam firmissimumque vallum_), strengthened with numerous towers, from sea to sea, over a space of one hundred and thirty-two miles. Cassiodorus, who wrote A.D. 520, gives a similar testimony. Among the events of the consulship of Aper and Maximus (A.D. 207), he enumerates the transference of the war by Severus to Britain— Where, that he might render the subject provinces more secure against the incursions of the barbarians, he drew a Wall (_vallum_) from sea to sea, one hundred and thirty-two miles in length. [Sidenote: VALUE OF THEIR TESTIMONY.] Such are the statements of the Roman historians respecting the authorship of the Wall. Several circumstances tend to invalidate the claim which they make in behalf of Severus. The first author who attributes the Wall to Severus is Spartian, a weak writer, who lived in an ignorant age, and nearly a century after the time of Severus. Surely his assertion will not be allowed to outweigh the negative testimony of Herodian and Dion Cassius, the contemporaries of Septimius Severus. Of all the authors who mention the length of the Wall, the only one who approaches correctness is Spartian, when speaking of the Wall, which he states that Hadrian drew from sea to sea; eighty Roman miles is very nearly the true length. The other writers call it thirty-two, [Sidenote: SPARTIAN INCONSISTENT.]or one hundred and thirty-two. Admitting, as some have supposed, that the larger number is an error, occasioned by some careless transcriber’s inserting in the copies the centurial number (C), which did not exist in the original, the difficulty is not removed. Thirty-two Roman miles is the length of the Barrier of the Upper Isthmus, not of the Lower, and these writers seem to have confounded the one with the other. Buchanan, Usher, and several writers, who were as capable of weighing the evidence furnished by the ancient historians as we are, have accordingly maintained, that the Wall which extended from the Forth to the Clyde, is that which was reared by Severus. This opinion we now know, from the inscriptions found upon it, to be erroneous; but the fact that it was entertained by such able scholars, proves the incompleteness of the historic evidence upon the subject. Milton correctly estimates the vague nature of this testimony. He writes—