Deploying the Army for Battle

The discussion of just how the army deployed for battle has to begin with the camp. The Romans fortified a camp at the end of every day's march. Every day. That means, unless their marching column were ambushed, they always went into battle from their camp, not from a marching column. Battles were accepted, seldom forced. That is, the defenses of even a poorly constructed camp, gave the defenders such a significant advantage that these camps were seldom attacked directly. When the Roman general led his army out of his camp for battle he had already selected the site of the battle and determined in advance the disposition of his army. Battles were usually fought within a mile or two of the camp. Because armies required open ground, camp and battle sites were selected on sites that offered unimpeded movement of troops between the camp and the battlefield.

The process of deploying the army for battle will be treated in five phases. The first two phases take place in the camp itself, they are : Planning the Battle and Exiting the Camp. The other phases are: Assembling the Army, Marching to the Battlefield, and The Battle Formation.

Planning the Battle

There is good reason to believe that a competent general would meet with his unit commanders to plan the battle. Once the battle actually started, communication between the various units would be difficult, at best. It would be essential for all everyone to know the plan well in advance. There are numerous examples in which generals went into battle with unusual battle plans -- Pompey's plan to hold back his infantry charge at Pharsalus, for example. These kind of tactical decisions could really only have been fully explained before the battle.

Who would the general meet with? It is important to keep reminding oneself that there were no rules. Each commander may well have done things differently. Almost certainly the commanders of each legion, auxiliary force and ala would be at the meeting. In some cases it would seem likely that the primi pili of each legion would also be there; as the senior non-coms they would have the most intimate knowledge of the status of their troops and may well have had the most military experience.

It is not difficult to imagine some of the things that the general and his commanders would discuss.

Manpower Assessment: Determine the manpower status of the army based on information from unit commanders. Establish the number of able bodied soldiers in each unit available for the battle.

Scouting Reports: Review the reports from foraging parties, scouts and spies to estimate the probable strength, disposition and intentions of the enemy army.

Select Battlefield: Choose a specific location for the battle based on information about the local terrain and factoring in the relative sizes of the two armies. Determine acceptable and unacceptable sites. Identify physical features that could create obstacles for the army, offer advantages to the enemy or pose opportunities for concealment or ambush by either side.

Survey: It seems possible that at least some of the time armies actually laid out marks on the ground in advance to guide the deployment of the army on the morning of the battle. If this were to be done, the status of the survey would be reviewed at the general's meeting.

Schedule: Set time for various activities on the day of battle such as when the morning meal must be completed, a time for mustering out of the camp, time for deploying the army in its battle configuration and even a preferred time for starting the actual battle itself.

Deployment of the Army: Decide the overall length of the infantry front, the depth of the formations, number of lines, placement of the light infantry and cavalry. Armies sometimes used two lines, sometimes three. They always tried to match the length of the enemy's line. The depth of the formations were sometimes changed because of terrain or to better match the enemy army formations. Two examples where the Romans adopted formations deeper than normal are the lines at Cannae and Pompey's lines at Pharsalus.

Location of Specific Units: Fix the location of each legion and other units in the line of battle. Caesar liked the tenth legion to be on the right. Auxiliaries were sometimes placed in the middle, sometimes on the flanks. Under-strength units might even be combined (Caesar). Cavalry might be placed on one or the other or both flanks. The light infantry could be used in a variety of ways.

Command Positions: Fix the generals command post. Generals might lead from the left, right or center of the army, even from the back. It would be important that everyone knew where he planned to be, at least at the start of the battle. There typically were commanders for the left, center and right sections of the army as well. The planning process would not only identify these commanders but would, very likely, also establish a general location for their field headquarters so that all of the other officers and messengers would have a general idea of their positions.

Order of March: Based on the deployment plan, determine the sequence in which each unit should exit the camp and the gates to be used. Identify the general route of the march to the point of assembly. If survey markers were set out, instruct the units which markers to use.

Battle Plan: Communicate the specific tactics planned for the battle. At Pharsalus Pompey held back the infantry charge so that his superior cavalry could attack Caesar's flank. Hannibal often set traps or used special formations. All generals tried to take advantage of any natural features that might give them advantages.

Artillery: Decide on the use and placement of artillery. Pompey assembled his army within the range of his artillery mounted on his camp walls.

Fortifications: Decide on the use of any fortifications. Caesar used field fortifications to protect his flanks when natural features were not available.

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.