Agricola was recalled by Domitian after seven years' warfare, and his
garrisons did not long hold their forts on his lines or frontier, which
stretched across the country from Forth to Clyde; roughly speaking, from
Graham's Dyke, east of Borrowstounnis on the Firth of Forth, to Old
Kilpatrick on Clyde. The region is now full of coal-mines, foundries,
and villages; but excavations at Bar Hill, Castlecary, and Roughcastle
disclose traces of Agricola's works, with their earthen ramparts. The
Roman station at Camelon, north-west of Falkirk, was connected with the
southern passes of the Highland hills by a road with a chain of forts.
The remains of Roman pottery at Camelon are of the first century.

Two generations after Agricola, about 140-145, the Roman Governor,
Lollius Urbicus, refortified the line of Forth to Clyde with a wall of
sods and a ditch, and forts much larger than those constructed by
Agricola. His line, "the Antonine Vallum," had its works on commanding
ridges; and fire-signals, in case of attack by the natives, flashed the
news "from one sea to the other sea," while the troops of occupation
could be provisioned from the Roman fleet. Judging by the coins found by
the excavators, the line was abandoned about 190, and the forts were
wrecked and dismantled, perhaps by the retreating Romans.

After the retreat from the Antonine Vallum, about 190, we hear of the
vigorous "unrest" of the Meatae and Caledonians; the latter people are
said, on very poor authority, to have been little better than savages.
Against them Severus (208) made an expedition indefinitely far to the
north, but the enemy shunned a general engagement, cut off small
detachments, and caused the Romans terrible losses in this march to a non-
existent Moscow.

Not till 306 do we hear of the Picts, about whom there is infinite