Once an invading Roman army had secured an area and moved on, the general would often leave behind a small garrison, usually of auxiliaries, housed in semi-permanent structures built of turf and timber, in order to police the recently-subdued natives and also to secure the retreat of the army should it become necessary. Occasionally these would be augmented by the construction of a larger legionary camp or fortress to provide strategic reinforcements, perhaps also by a system of signal-stations or watch-towers to provide communication between these permanent fortifications. There is ample evidence that Agricola instigated the construction of many such fortifications in the wake of his army, also that he planned to complete the conquest of Scotland aided by the construction of several large forts situated at the mouths of the glens leading into the Central Highland Massif. These “Glen” forts would be used as “springboards” to launch his army into the heart of the Highlands, and would be provided with support from the rear by the building of a new legionary fortress at Inchtuthil Roman Fortress on the Tay. Although it is possible that these permanent installations were initially laid-out during the tenure of Agricola it is very likely that the forts were actually completed by his successor to the post, Sallustius Lucullus, a governor who was also to fall foul of Domitian, but, unlike Agricola, was recalled to Rome and put to death, no doubt in some grisly manner, as was the modus operandi of this deranged and megalomaniacal emperor.

It is likely that work started on the Inchtuthil fortress no earlier than 85AD, the year after Agricola left Britain. This legionary base was abandoned uncompleted perhaps in the winter of 85/86, certainly by the summer of 86 when the removal from Britain of Legio II Adiutrix for use in Domitian’s Dacian wars forced the Twentieth Legion to be withdrawn from Scotland to maintain the garrison at Chester, recently vacated by the Second.

At the same time as the Inchtuthil legionary base was being built, a number of forts were also constructed at the mouth of each glen leading into the Caledonian highlands, to the south-east of Inchtuthil at: Barochan on the Clyde, Drumquhassle at the SE corner of Loch Lomond, Malling at Menteith, Bochastle at Callander, Dalginross at Comrie and Fendoch at the mouth of the Sma’ Glen, also to the north-east at: Ardoch, Strageath, Bertha, Cargill, Cardean and Stracathro. There may also have been another fort situated in the anomalously large gap between the latter two forts.

Ardoch may have been garrisoned by an auxiliary unit and a legionary cohort, and excavations at Fendoch and Cardean have demonstrated that both forts were evacuated after only a short occupation period. A number of bronze asses of 86AD have been uncovered at a number of military sites in Scotland; Inchtuthil, Camelon, Strageath, Stracathro, Crawford, Newstead, Cramond, Castledykes and Barochan. The finding of these coins, all in almost unworn condition, proves that all of these sites were garrisoned in that year or shortly afterwards. It is almost certain, given the stong garrisons in the glen forts that the Romans intended these camps to act as a springboard into the Caledonian highlands along the lines of the Glens. These plans were halted by the advent of war in Dacia.

“The abandonment of Inchtuthil was almost certainly accompanied by the withdrawal of the garrisons of the glen forts.” (Breeze, p.61)

Dispositions During the First Flavian period (85-ADc.90)

• Large Forts – encampments in excess of 7 acres (2.8ha).
• Medium-Sized Forts – camps between 3½ to 6½ acres (1.4 – 2.4 ha).
• Small Forts – camps around 1 acre (0.4ha).
• Fortlets and Stations – smaller camps with no administrative buildings.