Exiting the Camp


It may be good to begin with a quick overview of just what exiting the camp would have entailed. The Roman camp was fortified with walls and ditches and had only 4 small gates. Gates were just openings in the wall blocked on the outside by defensive works to keep an enemy from just riding right through them. But if they were awkward to get into, they were equally awkward to get out of. As will be discussed later, it seems likely that only 4 columns of two men abreast could pass through a gate. The army that is being modeled, the Generic Army, has about 20,000 foot soldiers and around 5,000 cavalry. All of these men have to maneuver between the tents, get themselves into some kind of order, and squeeze themselves out of one of the four gates of the camp in as short a time as possible. If total chaos is not to occur, the entire process has to be highly organized.

It it that process that will be explored on this page. There is only meager historical evidence to use; much of what is presented is based on guesswork, plain and simple. But guesses based on what we do know and on what is most reasonable. Altogether, in spite of the dearth of ancient evidence, a fairly good picture can be developed; perhaps not accurate in all respects, but hopefully an improvement over the simple generalization that "the army left the camp." At the very least it is hoped that these pages will create an environment that stimulates additional thinking on the subject.

The Tenting Spaces

The best way to begin is to consider the arrangements of the tents and the spaces provided. This is based on the material presented in the paage Camp Size.

The illustration shows two versions of a small portion, about 1%, of the camp's tenting area. It shows the tenting areas for three centuries of infantry and two turmae of cavalry. The right side of the drawing shows these areas as represented by symbols. The three rows of red U's are the tents of the three centuries of infantry, the two rows of blue U's are the tents of the two turmae of cavalry. On the left half of the illustration the same units are shown in a more realistic manner. As noted in Camp Size, the cavalry contubernia may have required a second tent for servants and equipment but, for the sake of clarity, the second tent was omitted from the symbols and only a single blue U was used. On the realistic side of the drawing there are two tents per site. The last tent on the left of each row of is a single tent for the officer.

There is much to note about the illustration. The broad dark greed swath at the far left represents the via praetoria, the main street of the camp; it is 100 pedes wide. On the left side of the street are two columns of infantry and one column of cavalry which come from the tenting sites on the other side of the street. The two longest columns represent one entire century and one turma. The century is nominally 80 men strong, but due to inevitable absences, all units in all armies at all times are almost invariably understrength. This is reflected in the illustration: there are only 65 soldiers plus a centurion and an optio, the lone figure at the back of the column.

It is of great importance to note is that the geometry of the camp itself dictates how the army has to move to exit the camp. The routes for troop movement are created from the open space at the ends of each contubernium's campsite. When placed together in rows these open spaces create lanes of travel. These lanes are colored darker green. Each tenting area contributed 5 pedes to these lanes. The two lanes of the facing tents were 10 pedes wide, enough space for 4 men or horses abreast. If each century used only its own half of the lane then it could only move out of the camp in a column-of-two's.

Of course, the century could use the wide streets or the intervallum to reassemble into almost any number of ranks and files it wished. But to pass through the gates it would have to have to re-form into a column-of-two's or, perhaps, four's. There would be little point in having the unit go from a column-of-two's to a rank and file formation and then right back into a column-of-two's or four's again to go through the gate. It is therefore deemed most likely that the century and turma would stay in a column-of-two's from the time it left the tenting area until it was clear of the gates at least.

This is an important factor in considering how the army maneuvered and will influence all future troop movements right up to the final deployment at the battlefield

The width of the camp's main streets would allow several columns to move along it at once, 6 easily, perhaps 8 or even 10. The illustration envisions the cavalry taking the middle of the street and the infantry on the sides.

The next two illustrations show the the drawing in more detail.


The two arrows point to the optiones of each of the two centuries.

The century at the top is shown as it just starts to march away. The centurion on the far left leads, followed by the signifer and cornicen. Notice that there are gaps in the century formation on the bottom but there are not any gaps in the century on the top. The gaps appear because the unit is understrength. In the top century the optio (red arrow) fills in the gaps by moving men forward as the column steps out. A close look at the previous illustration, which shows the entire century, will show gaps remaining in the contubernia further to the right where the column is motionless. The soldiers there are closer together, as they are in the bottom century.

The century at the bottom is still assembling itself. A few contubernia at the right are fully assembled, several are scrambling to form up. The optio oversees the whole process. At the front of the column the signifer and cornicen are in place, ready to lead. The centurion is turned facing the column, waiting for a sign from the optio that the entire company is assembled. There are gaps in several of the contubernia where men are missing.

This role for the optio is purely speculative, but it seems obvious that the centurion at the head of the column might need some assistance to order things at the far end and apprise him of the status of the formation. If not the optio, then almost certainly some other soldier fulfilled this function.

What should stand out above all is the enormous complexity of moving 20,000 men out of a large camp in columns-of-two's, bringing them out through two or three different gates and re-assembling them all in their correct units somewhere outside the camp. From an examination of just this small piece of the camp it can be seen that coordination would be critical. Each century and turma has to be moved in sequence and on time and has to follow a prescribed route. The potential for the process to degenerate into a hopeless tangle of confused units is enormous.

Delbruck notes that the Romans were superior to their enemies, not necessarily so much in tactics as in their organizational ability which enabled them to effectively field large armies. This is but yet one more small example of this quality of the Roman Army.

The Camp Gates

After assembling in front of their tents, forming a column and then marching out into the viae, the columns would proceed to the camp gates. The illustration below shows the intervallum between the tents and the camp gate.

The previous drawings of the tenting area are at the bottom right. This illustration shows the 200 feet of the intervallum and the camp gate. The tents that would be in the black rectangle at the bottom left are not illustrated.

The information about just how camp gates were constructed is not particularly detailed. It seems that no actual gate was involved, merely a gap in the defensive wall which was protected by berms either inside and outside or just outside. The illustration shows U shaped defensive works both inside and outside the gap in the wall.

Several columns are shown passing through the left side of the gate. The columns that would pass through the right side of the gate are not illustrated to avoid undue clutter to the illustration.

The depth of the intervallum gives the columns time to organize themselves. It would certainly be possible for the century to assemble in its parade-ground formation inside the walls, but since it has to reduce itself to no more than 4 files to pass through the gate, there would seem to be little purpose to having it re-form first. Instead, it seems likely that columns would keep their marching formation while waiting their turn to pass through the gate.

The gaps between units would be important to keep the whole process moving along at a reasonable speed

The illustration below shows a close-up view of the gate itself. The gap in the walls that form the gate is 40 feet wide. The gap between the walls and ends of the U shaped defenses is 20 feet.

It might seem that more than two columns could pass through the 20 foot gap on each side. That would be true if there was a straight route through the gate. But gates were made to obstruct passage; after all, the purpose of the camp was to defend against attacks. The illustration shows that it would be rather congested for more than two columns to make the necessary turns.

Because of those turns the columns would not be able to move at a normal pace. A good walking pace would be about 3 miles per hour, however, columns like these would probably do well to average 2 miles per hour through the turns of the gate.

The Generic Army has roughly 20,000 infantry soldiers and 3,500 cavalry. If they march in columns of two that makes 10,000 ranks of foot and 1,750 ranks of horse. 2 mph is 176 feet per minute. Marching infantry would take 4 feet per rank and cavalry 12 feet per horse. That makes the columns-by-two for the infantry 40,000 long and the one for the cavalry 21,000 feet long. If 4 columns can pass through one gate side by side then it would take 57 minutes for the infantry to pass through and 30 minutes for the cavalry, 1 hour 27 minutes for the entire army. If two gates are used then the time is 43 minutes; 3 gates, 29 minutes; and 4 gates, 22 minutes.

There is not much that could be done to speed up the exiting process. Camps were for built for defense and to keep the enemy out. They were defended during the battle (artillery on the walls, detached units as large as legions, perhaps armed camp servants) and to be safe refuges after the battle as well as before it. Any change that made egress faster and easier would correspondingly weaken the camp's defensive capability. The gates may have been 50 or even 60 feet wide, but would always have hindered free passage.

The Exit Routes

The army being modeled is the Generic Army. It is comprised of 4 legion sized forces (all called simply "legions") 12 alae of cavalry and 8 centuries of light infantry. In addition, there is one cohort each of evocati and bodyguards. The arrangement of the units within the camp generally follows the standard arrangement to be found in almost any book on the Roman army. But, as was noted previously, there could not have been anything permanent about the arrangement since the size of the camp would change as units came and went. And, whenever the camp size changed, of necessity, the placement of individual units would have to be shifted and adjusted.
Based on the arrangement of units the illustration below shows the exit routes using three of the four gates.


Red: Legion I

Green: Legion II

Blue: Legion III

Magenta: Legion IV

Dark Green: Cavalry

Orange: Evocati

Purple: Bodyguards

Not Shown: 8 Centuries of Light Infantry

There are several reasons for not showing the exit routes of the light infantry. There are only 8 centuries of them so the manner in which they exit the camp is not a major concern. But, more importantly, as illustrated on the left, they are scattered around inside the camp and trying to show all of their small arrows would unduly clutter the illustration.

In the illustration only three of the four gates are used. This is because it is considered likely that the camp would rest one side on some type of natural defensive feature, limiting the free flow of troops on that side. If four gates were used, Legion IV could simply exit out the back. The overall diagram would change little.

Links to the five parts of the Deployment section:
Deploying the Army: Planning
Deploying the Army: Exiting the Camp
Deploying the Army: Assembling the Units
Deploying the Army: Marching to the Battlefield
Deploying the Army: Forming in Battle Formation

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2003, Gary Brueggeman. All rights reserved world wide. No part of this work may be reproduced in part or whole, in any form or by any means, without permission from the author.