I have reviewed every Roman fort listed on Canmore and used the rough dating from that site for the forts on the map below. A few forts had multiple periods of occupation and it was hard for the archaeologists to understand what they were looking at. Where there is a comment in Canmore about an earlier Agricola fort I have included it on this map. Sites which are said to exist “with certainty” but without any material evidence I have generally not included. Inveresk/Musselburgh I have included as a harbour supply point which may be personal bias. Roads that served later forts I have not included. It’s not an exact thing but from the size of forts it appears around 30,000 troops may have been involved in occupying Scotland. This excludes any civilian settlements, auxiliary forts, unknown forts and the many harbours or landing points that might have existed.
Agricola’s son-in-law Tacitus wrote a book about the campaign. He writes “Persons of experience remarked, that no general had ever shown greater skill in the choice of advantageous situations than Agricola; for not one of his fortified posts was either taken by storm, or surrendered by capitulation. The garrisons made frequent sallies; for they were secured against a blockade by a year’s provision in their store.“
A line of forts between the Clyde and the Forth were built “The fourth summer was spent in securing the country which had been overrun; and if the valour of the army and the glory of the Roman name had permitted it, our conquests would have found a limit within Britain itself. For the tides of the opposite seas, flowing very far up the estuaries of Clota and Bodotria, almost intersect the country; leaving only a narrow neck of land, which was then defended by a chain of forts. Thus all the territory on this side was held in subjection, and the remaining enemies were removed, as it were, into an other island.”
An interactive map is below
The maps with distances between forts are below as a slideshow
I have tried to calculate how many Roman troops were stationed in Scotland. I used sizing information from those Roman forts whereby an estimate has been given for a number of soldiers per hectare of a fort. Applying this to the forts in the spreadsheet gave a combined figure of 30,000 troops stationed inside forts. This figure does not include auxiliary spaces next to the fort, no civilian areas nor does it include the camps used for campaigning. It assumes all forts had roughly the same layout and does not account for proportions of cavalry to troops in a fort. So it is very rough but it gives an idea of scale.
The figures can be found here in a google sheet Roman Forts Size Feel free to feedback.