These were consuls in A.D. 158; consequently, we have undeniable authority to assert, that Antoninus Pius repaired Hadrian’s Vallum (or, at least, the stations per lineam Valli), as well as built one between the Scottish Firths. This stone is certainly most valuable, as it clearly proves, that though Antoninus extended the boundary so far north, he could not, or durst not, trust the Mæatæ, but thought himself obliged to keep up the southern pretenturæ, lest they should, on any disturbance, join the Caledonians.

Such prudence is characteristic of good generalship. Napoleon never made an important move without first resolving what to do in case of failure. Assuredly Hadrian did not act in a manner unbecoming a Roman, when, at the same time that he shewed a stony front to the Caledonians, he placed an earthen rampart between himself and the doubtful fidelity of his southern subjects.

THE BARRIERS IN RELATION TO THE RIVERS.

The position of the Barriers of the Lower and of the Upper Isthmus, and of the Devil’s Wall, in relation to the rivers in their vicinity, requires some remark. The Tyne in the eastern, and the Irthing and the Eden in the western part of the island, are uniformly to the south of the English Wall. A similar remark applies to the Devil’s Wall, in Germany, which is drawn along the northern shore of the Danube, the side exposed to the enemy. The Clyde, and its feeders, are to the south of the Antonine Wall. Why did the Romans not avail themselves of the natural trenches of these river-basins? The valley of the Tyne is peculiarly broad and deep. A chain of camps on its southern bank, where the mediæval castles afterwards stood, would alone, we might suppose, have bid defiance to the passage of any foe.

A similarity of practice in these cases favours the belief that important objects were to be accomplished by it. What are they?—

By erecting a chain of posts on the high grounds to the north of the rivers, a better observation of the movements of the enemy was obtained than would otherwise have been practicable. In the days of Roman occupation, large tracts of country, the banks of rivers especially, would be covered with forests. The conquerors, unless they had secured the enemy’s side of the river-basins, would have been perpetually subject to unexpected attacks. They could not be so easily taken by surprise on the high grounds of the northern slopes.

IMPORTANCE OF RIVER BASINS.

Probably the value of the land on the margin of the rivers, was an additional motive for the course pursued. The alluvial soil by a river’s side is usually the most fertile portion of a country. The banks of the Tyne and the Eden are peculiarly productive. Without a wall the enemy would have had undisputed possession of the slopes which enjoyed the finest aspect—that to the south—while those on the other side would have been subject to frequent depredation. This consideration is of the more importance, as the lands of the district were given to the soldiers who garrisoned the frontier, as a means of securing their fidelity.

PRUDENCE OF THE ROMANS.

So far from the importance of the natural boundary, the river, being overlooked by the Romans, I am disposed to regard the works on its northern bank as a proof of the value which they set upon it. The natural and the artificial barriers were probably regarded by them as but separate members of one complete fortification. In case of a rush of invasion from the North, the Wall would arrest the attack and the river entirely repel it. The stone and earth works would impede the progress of a foe, however formidable, and give time for the formation of an army on the southern bank of the stream. It was, moreover, ‘political in the Romans,’ as Stukely remarks,[[53]] 'to leave on the north side of the Wall that huge tract of waterless and dismal moor, a great barren solitude, where in some places you may walk sixty miles endwise, without meeting with a house or tree; to ride is impracticable. Thus, as much as in them lay, without the horror of barbarity, did they remove the barbarians from their territories; whilst within the Wall, either naturally or by their industry, all things smiled like the garden of Eden.'