The Orientation of Roman Camps and Forts

Blackwell’s have made an issue of the Oxford Journal for Archaeology accessible to the public. This is a particularly good one for me as it includes a paper by A. Richardson, The Orientation of Roman Camps and Forts. In some ways it’s slightly annoying as it was something I planned to look at after completing my thesis, but it’s a good illustration of work that could be done by anyone with an interest in ancient astronomy. The paper looks at cardinal alignments in Roman camps and forts. A typical Roman camp is a playing card shape and there is a tendency for camps to be aligned to the major compass points. If celestial alignment wasn’t an issue then you’d expect the alignments to vary in all directions. Still, it would be odd if all camps had the same alignments because in some places it would be simply stupid to rigidly adhere to a rule, like if your major exit led out over a cliff edge. True, there are some mileforts on Hadrian’s Wall that do this, but not all of Hadrian’s Wall makes military sense anyway.

In terms of method it’s done well. The author takes into account that grid north on an Ordnance Survey map and true north are not the same, which I think I might have overlooked if I were working from maps. Because the project is map based I do have some concerns about how accurate the plans he was working from are. In my own experience north can vary even within the same site report because some archaeologists aren’t that interested in accurate orientation. Over the scale of this survey though it’s not going to make a huge difference. Richardson has also given some thought as to the practicality of how the camps woulld be laid out. His examination of whole number ratios for the sides makes sense. He also thinks about how a solar compass could be used for finding true north.

One possible astronomical guide he may have overlooked is the use of shadows in laying out baselines for building a camp. If you stick up a ranging rod in the late afternoon then it’ll cast a shadow on the ground. Pull out a rope along the shadow and you have a baseline, though I don’t know if there’s evidence the Romans did this. If they did I’d expect a tendency for alignments to veer slightly east of north. My reasoning is that you’d mainly be marching during the summer and in the summer the sun sets north of west. If you leave setting up camp till the late afternoon then you’re more likely to be slightly askew to the east of north. I’m very possibly wrong on this though, so maybe he thought about it and disregarded it as an explanation.

The only place I’d possibly disagree with him is in his conclusion “The use of a limited number of offset angles was probably due to a religious regard for celestial geometry.” There are possibly good practical reasons for having a set procedure for setting up a camp. Everyone knows where they are and what they’re doing and the less time spend setting up camp, the more time you have for marching. To some extent that’s hair-splitting though, as the practical reasons could have been encoded as religious beliefs. In this era there wasn’t the divide between the rational and irrational that exists today, so setting up an argument practical versus religious is anachronistic. —–