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Marching camp construction
(01-13-2019, 01:25 PM)Stug50 Wrote: It would be unusual for any large military force to move through territory, occupied or hostile without sending out advanced reconnaissance. Varus for example allegedly made the mistake of detouring through unfamiliar territory without using reconnaissance, I suppose he decided that he had good enough intelligence based on information from Arminius the result of which ended in a massacre. 
I’ve read various reports that state that some of the Romans’ managed to set up a camp at night with hastily built defences which they were able to use with some limited success but they ran into trouble when they tried moving on from the camp. 

That will be chapter 20 hear:*.html

I've been trying to find any mention of finding these defences at Kalkriese but cannot find anything.

(01-13-2019, 01:25 PM)Stug50 Wrote: Of course this is all conjecture on my part but I would think that various contingency plans would have been the norm for moving such a large body of men and equipment. I’ll leave it to those with far better knowledge than myself to debate how the Legions were organised when moving from camp to camp.

I found this which interest you:
Thank you for the links. 
I recall watching a documentary (YouTube) where an archaeologists thought that he had found evidence of the night camp, the problem was only a few artefacts had been found in the area but he did argue that the location which was in a clearing near the edge of the forest was a highly probable location. Frustratingly, I can’t remember the name of the documentary but if I find it again I’ll be sure to post a link. 
To be honest I really don’t think that it’s possible to find any hard evidence of that night camp, the archaeologists would probably be better off looking for evidence of the continued slaughter which happened as the remaining Men of the legions made a run for it. Perhaps if enough Roman artefacts were excavated in a particular area they could potentially indicate the probable area of the camp.

A link to brief article on the temporary camp at Kalkriese.
(01-10-2019, 09:03 PM)Jason Micallef Wrote: if they constructed fortified camps for detatchments of soldiers.

This has come up a couple of times before:

Marching Camps for Small Detachments

Small Unit Camps?

And this thread might be interesting too:

Single century sent on missions/patrols?
Nathan Ross
Thank you. Smile
The following is scribbled quickly without too much use of 'probable', 'maybe' etc.

There were probably simple rules/guidelines for the camp layout which a 'surveyor' would know for the size of his force. Key consideration would be the orientation of the area assigned to each contubernium relative to the short or long sides of the camp - expect this would be decided before the force started to march. Once this is decided the total space, the lengths of the camp sides, placing of tented areas, intervallum and the dividing 'clear areas' or interior roads etc. are all predetermined.

So, arrive at camp site; mark out the short side and deploy two groma at each end. The mid-point of this side is the site for the Porta Pratoria. The side is marked at the outer edge of the proposed rampart. This is because the first job for the construction crew is the cutting of turves for the rampart. It makes little sense to cut turves inside the camp or under the rampart. The line for the sides was probably marked as a visual aide by the first turves, i.e. at the outer edge of the rampart. The same could be done for the midline of the ditch but this probably not really necessary for an experienced force. Using the turves to mark out the camp elements is quite simple, effective and, once done, releases the surveying crew to move elsewhere.

The rounded corners are simple to engineer using a length of string: place one end at the groma and run it back down the short side; now release the end at the groma and rotate it at 90 degrees into the interior of the camp, i.e. the string is perpendicular to the camp side; fix the interior end of the string and then rotate the other end to describe on the ground a constant radius curve which is the outer margin of the curved corner of the rampart - lay turves as the string rotates. Simple, practical and the four corners of the camp will describe the same arc if one piece of string is used.

Now use groma and sighting staffs to sight along the proposed long sides (the groma if used correctly will give 90 degree angle between short and long sides). Mark out using turves as they become available.

It isn't necessary nor desireable to complete the survey of the full circuit of the camp before ditch excavation and rampart building start - the surveying can continue quite simply down the long sides as and when required. An obvious benefit is that the defences are built quickly - the long sides are extended - by the soldiers as they arrive in the camp. Having an open-ended construction technique also allows flexibility in the overall size of the camp, i.e. the long sides can shrink or grow depending on the number of units in the force. Plus, without the final short-side yet surveyed or built then the force still marching can simply flood into the camp and set-up tents etc. where they normally do.

One of the last acts would be to seal off the long sides with the construction of the remaining short side, that which contains the Porta Decumana.

Two groma, some sighting staffs, a length of string and lots of turves - all very simple technology and techniques. Simple enough for a few bright soldiers to be taught how to use the groma etc. - no need for a well-educated man to accompany each force in the field; save him for teaching, building forts, ports, towns, temples, planning roads and for deploying with very large armies requiring large camps.

To state the obvious, there is one prerequisite that all armies through time rely upon, experienced men. Without them then the description above would probably be untenable or take a long time.

Some answers to questions above:

1) How long to build a camp = 2.5 to 3 hours for all force sizes, for nearly all camp sizes and metrics (ditch depth, etc.).

2) The Romans used relatively small numbers of well-trained, well-equipped men to conquer and control. During daylight hours these samll forces were usually capable of defending themselves against much larger numbers of enemies. However, without a night-time, defensive stronghold - the marching camp - the small Roman force would be overwhelmed. Darkness was the legionary's nemesis, not marching in columns during daylight - usually!

3) How many turves for a camp? One legion, builds a camp 276 x 351 m in size, using 30% of the force, within 2.42 hours. A rampart built of walls two turves thick, infilled with soil from the ditch, 2 m wide, 1.1 m high and with a fighting platform 1.2 m wide would require 520 turves, each of volume 0.01945075 cubic metres.

If you like playing with a few numbers relating to Romans on campaign then I can recommend a spreadsheet here and an accompanying, descriptive document here.  You need the document to use the spreadsheet. Splendid stuff!
A quick review of the relevant sections of Polybius and Josephus would certainly help. A number of elements that have been discussed here are detailed and many more can be interpolated. Advance guards, vanguards, scouting and parties to lay out the next camp; as well as comments as to advancing with and without facing the enemy are all mentioned.

In contrast to the above - Polybius is quite specific and the layout of the camp starts with the position of the Consul's tent. That said, I have also found the dimension of the 'short side(s)' to be easily determined - given that I am quite sure that the length of that side is exactly equal to the deployed frontage of the 2+2 legion Consular Army structure - with a gap for the gate. However, yes - all that is needed is a groma, spears and rope/string would indeed be useful (my personal desert island choice is a ball of para-cord!) - along with some standard roman-pacing.

Compared to the Polybian camp structure and the parallels I have seen in much later fortifications; I must admit to being extremely sceptical about the over-complexity of 'Hyginus'.
Excellent thank you. According to ‘The complete Roman Army’ written by Adrian Goldsworthy, he mentions that 10 men from every century would be tasked with ‘carrying their own kit and equipment for marking out the camp’, if that’s correct and my math is right that means 600 men per legion tasked with carrying surveying equipment but in your description only two groma would be required to set out the sides of the camp, perhaps I have misinterpreted Mr Goldsworthy quote! I wonder if what he was referring to were specialists troops that had the ability/skills to survey and construct these camps. It would certainly make sense to have at least ten men in each century that had the necessary surveying skills.
Once again thank you for your interesting and helpful post.
Yes, the 10 men per century is a direct comment from Josephus - and my personal interpretation is that this is very likely to be 1 from each contubernia indeed. Moreover I believe these are most likely exactly half (so 2 per contubernia) of the 'antesignanii'; along with the 'guards' around the general - both of which precede, therefore, the standards on the march (cf Josephus again). These are armed and armoured slightly differently to the rest of the legionaires and carry spears/hasta rather than pila, which would be much more useful in marking out a camp. Each of those original 10, if they are one per contubernia (and provided security from attack) could even place their own kit directly on the contubernia's tent site.

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