Age of Reason

The frontage covered by a unit in its normal fighting formation has a huge bearing on how an army deploys for battle. Typically, European troops, particularly Infantry, closed ranks once stationary in battle position. When they marched, particularly, when not in actual combat, the ranks opened somewhat, to allow for ease of movement. Equally important is the road space taken up by units when an army marches between locations. The following table lists the frontages of units in typical formations of the early Eighteenth Century and their depth in road column. Assumed strengths are 720 men per Infantry Battalion and 150 men per Cavalry Squadron.

Unit	Frontage Stationary	Frontage, Moving
Infantry Battalion, 3 deep	160yds	240yds
Infantry Battalion, 4 deep	120yds	180yds
Infantry Battalion, 5 deep	100yds	150yds
Infantry Battalion, 6 deep	80yds	120yds
Infantry Battalion in Column	30yds	40yds
Infantry Battalion in Square	30yds	40yds
Russian Brigade Square	120yds	150yds
Infantry Battalion in Road Column	-	500yds deep

Cavalry Squadron 3 deep	90yds	120yds
Cavalry Squadron 4 deep	70yds	100yds
Cavalry Squadron 5 deep	60yds	90yds
Cavalry Squadron 6 deep	50yds	80yds
Cavalry squadron in column	30yds	50yds
Cavalry Squadron in road column	-	300yds
Light Cavalry Squadron in line	150yds	150yds
Light Cavalry Squadron in swarm	100yds	100yds
Light Cavalry Squadron in road column	-	300yds deep

4 gun battery deployed	80yds
4 gun battery in read column		140yds deep
6 gun battery deployed	120yds
6 gun battery in read column		210yds deep
8 gun battery deployed	160yds	-
8 gun battery in read column	-	280yds deep

In the 18th century, the normal frontage, for artillery was 19yds per gun. This allows the gun team to deliver the gun to its firing position, recover it and turn without hindering neighbouring teams. Guns deployed any closer will take considerably longer to deploy or recover. If done under fire, this practice will lead to considerable delay and could lead to self inflicted gun casualties as teams and guns collide.

At the start of the century, it was usual for European Armies to form up in two distinct lines. The units of the Second Line were deployed some 200yds to the rear of the first. This would put them safely beyond the range of any small arms fire aimed by the enemy at their First Line and flying over the target or otherwise missing it. Perhaps more surprisingly, the battalions of the First Line were drawn up with battalion size gaps between them. The Second Line, then drew up, corresponding to the gaps, thus presenting a Chequer Board formation, reminiscent of Ancient Rome. As a general rule, the artillery was drawn up in front of the Infantry of the First Line. This may represent theoretical rather than practical deployment; perhaps reflecting Age of Reason thinkers’ obsession with everything Roman.

An Infantry Column of 24 battalions, deployed in 3 rank deep line, in two lines in chequer-board, would cover a frontage of 3920yds, or just over two miles. This would give room enough to deploy the three to four Field Artillery Batteries that we could expect this force to have, in front of the Infantry. We might expect these to be joined by the force’s battalion guns, which might number up to 48.

A Cavalry Column of 12 Squadrons, deployed 3 deep, in two lines in chequer-board, would cover a frontage of 1,080yds, or well over ½ of a mile. A Light Cavalry Column of 12 Squadrons, deployed in two lines in chequer-board, would cover a frontage of 1800yds, or just over a mile.

Thus even a fairly small army; of 24 battalions and 24 squadrons, with the infantry deployed in the centre and two cavalry wings would cover a front of about 3 miles.

When moving strategically, Armies would adopt Road Column, one unit moving behind another. For large Armies, overall column length could assume mammoth proportions. This is an essential consideration for anyone running a campaign.

The above Road Column rates allow for very little baggage or additional ammunition to be included in the unit depths. Army baggage train and camp followers can be estimated to compose between an additional 50-200% of the Army’s total combat unit depth, dependent on how lean and well disciplined the Army is.

Thus an Infantry Column of 24 battalions with 4 batteries of Field Artillery attached would stretch 12,800yds (7¼ miles) without baggage, and between 20,000yds and 35,000yds including its baggage (11 and 20 miles). At normal pace of 2-3 miles per hour, such a column would take up to twelve hours to pass a single point.

Adding the Cavalry of our example Army of 24 battalions and 24 Squadrons, with 6 batteries would create a road column, 20,000yds (11½ miles) long, without baggage and up to 60,000yds (35 miles) including its train.

The above Column lengths are for a formation marching along a single road. In developed areas larger formations may be able to advance over a road net, rather than a single route. In good weather, some of the troops will also be able to move cross country, to relieve congestion on the roads. However, the artillery and baggage will always need a road and in bad weather most tracks and many roads would soon become virtually impassable to guns, carts and wagons. In mountainous or forested areas, off road movement would be difficult in the extreme, for Infantry and Cavalry and impossible for the Artillery and Baggage.

Choke points, such as bridges, fords or defiles, roads through forest or marsh would preclude any off-road movement to all, but light infantry and cavalry. At such places, the breakdown of a wagon or gun limber/carriage could result in delays for the whole army.

The answer to the problem of road capacity was sought in the Corps system of the Napoleonic Wars. This was an attempt to organise Armies into semi independent, self contained forces, called Corps, which could operate along a single road, or local road net. Several Corps could then advance along parallel or converging routes, to re-unite as an Army, at the designated destination. In theory, this enabled a large Army to advance upon a given target, without clogging up its own road net and without exhausting the countryside of supplies.

On campaign, illness and desertion take their toll on an Army far faster than battle casualty and so units entering battle were usually well below establishment strength. Average Battalion sizes for Marlborough ’s major battles are approximately 550 for the French and 600 for the Allies. Average Squadron sizes are around 105 for the French and 115 for Allied Squadrons. The following tables show a British Battalion on campaign, formed in three ranks and French Battalions in four to six ranks.

Unit	Frontage Stationary	Frontage, Moving
Infantry Battalion, 3 deep	130yds	200yds
Infantry Battalion, 4 deep	90yds	120yds
Infantry Battalion, 5 deep	70yds	100yds
Infantry Battalion, 6 deep	60yds	80yds
Infantry Battalion in Road Column	-	350yds deep

Cavalry Squadron 3 deep	60yds	80yds
Cavalry Squadron 4 deep	50yds	70yds
Cavalry Squadron 5 deep	40yds	60yds
Cavalry Squadron 6 deep	30yds	40yds
Cavalry Squadron in road column	-	200yds

This gives the Allies an average Battalion size of 681 men with a Squadron average of 136. Austrian battalions were very large, compared to Northern European or British formations, which probably explains the relatively large average battalion size. French average battalion size differs with the estimate of overall numbers. Following the Allied estimate of 60,000 men, French battalions average 563 and Squadrons 113. Whereas, following the French tally of 43,900 men, the average battalion has 407 men and the average squadron, a mere 81.