"He [Antoninus Pius] conquered the Britons through his legate Lollius Urbicus, another wall of turf being built after the barbarians had been driven back, ..."
Roman forts were first established in the lands of the Damnoni tribe along the isthmus of the Forth and Clyde during the fourth campaign season of Gnaeus Julius Agricola in 81AD (q.v. Agricola XXII.i). Built along the same isthmus some 60 years later, the Antonine Wall in Scotland was the northernmost permanent frontier of the Roman empire. The Antonine barrier consisted of a line of timber-built forts and fortlets connected by a continuous rampart wall of turf fronted by a wide ditch.
These entrenchments ran from Borrowstounness near Carriden in Edinburgh on the Firth of Forth, to Old Kilpatrick in the outskirts of Glasgow near Dumbarton on the Firth of Clyde, passing along the central valley of Scotland formed by the River Kelvin in the west and the Bonny Water to the east, a distance of 39 miles - exactly half the distance of Hadrian's defensive works 100 miles to the south. For the most part the defences were positioned to the south of these two streams, which themselves formed a natural line of defence against attack from the north. (q.v. Macdonald)
Modern investigations have revealed that the Antonine Wall was built in four discernable stages, the primary forts being constructed first at (from east to west) Carriden, Mumrills, Castlecary, Bar Hill, Balmuildy and Old Kilpatrick, and the rampart wall started in the east, then the wall was advanced to Castlehill with many of the mile-fortlets being added, following this, the secondary forts were built and finally, the curtain wall was completed in the west between Castlehill and Old Kilpatrick (Keppie, esp. figs.2/4).
The release of a series of coins, of all denominations, comemmorating these 'victories in Britain' point to there perhaps being a certain amount of propaganda attributed to the building of the Wall; Antonine certainly took steps to ensure that S.P.Q.R. were well infomed about his gains in Britain (Spink, 639-646)
On the continent, Antonine had similar ideas for the extension of the Rhine-Danube frontier. The southern section of the frontier in Upper Germany was extended from the Main beyond the Neckar between forts at Walldürn and Welzheim, and the entire Raetian frontier were moved forwards between 10 to 35 miles, giving a straighter line to the overland route between the two river barriers. The Rhine-Danube limes had now reached its ultimate extent, measuring 240 miles in Germany and 103 miles in Raetia. It is significant that these 343 miles of impressive frontier works, over nine times the length of his wall in Britain, is not mentioned on a single coin issue. (Williams, chap.7)
The advance from Hadrian's to the Antonine Wall in Britain was not sound strategy, however, the exercise being performed in order to enhance the emperor's personal gloria and dignitas. Certainly cost-cutting could not have been the reason, for although the Antonine barrier is under half the length of the Hadrianic frontier, there were more forts along its length, containing about 1½ times the garrison, not including the forts arranged along the arterial roads in the lowlands of the hinterland which also had to be manned (Williams, p.163).
The Antonine Wall was finally abandoned in 163 as a result of an uprising amongst the Brigantes tribe in northern England, against which Sextus Calpurnius Agricola, former governor of Lower Germany, was sent with several detachments from the German frontier in order to put down the rebellion (Augustan History, Antoninus Pius VIII.iv). However, the revolt of the Chatti across the new Antonine frontier in Upper Germany and Raetia meant that the manpower required to garrison and hold Scotland would not be available, being more urgently needed - from Rome's point of view - on the continent (Speidel).