Ancient and Medieval battles: going deep vs going long. Isn't going deep a terrible idea?

#1
In many ancient and medieval battle accounts, armies "went deep," which means they had multiple units behind one another, creating a deep sea of infantry. Opposed to "going long" which was where most if not all units were side by side, stretching out the line as far as they could in an attempt to flank and envelope the enemy army.

My question is this, wouldn't going deep always be a bad idea? Often in ancient and medieval battles units would get squeezed, this is exemplified in the battle of Cannae where Hannibal surrounded the Romans and squeezed them together. This was incredibly effective as the Romans were so tightly pushed together they had no room to thrust their weapons. In fact, in the center of the Roman army, men were so tightly packed that they were crushed to death or suffocated. For the Carthaginians, it was simply a matter of going through and slaughtering the defenseless Romans.

Many times while watching reconstructed battle accounts on YouTube, going deep was justified as "adding pushing power." But this makes no sense whatsoever, if the backline pushed against the frontline, all that would do is squeeze the frontline or just push them into enemy spears. And if the enemy frontline pushed, the backline would be working for them as it would help them squeeze the frontline. Meanwhile, you would have many thousands of men just standing around while your enemy who went long would have every unit fighting. Not to mention it makes enveloping and causing further squeezing much easier for the enemy. In the battle of Cannae, going deep certainly didn't add "pushing power." It seems any benefit to going deep could be achieved by just having units in reserve but further back so as to be dispatched to needed areas more easily and to not inadvertently squeeze your own units. So why was this done?


I don't know if this is the best place to ask this, if not I'd love to know the proper forum for this kind of question. Thanks.
 
Jan 2009
1,190
#3
Going deep gives you one big advantage: reserves. Even if your front line gets broken, there is another line of infantry step up and stabilize the situation. If you have only one line, then, generally, once that line gets broken, the whole army routs. Also, your 2nd and third line troops are rested, and if need be, they can be peeled off and respond to developments on the battlefield, like at Pharsalus.

Romans used triplex acies for centuries. Clearly it had something going for it. Here's what Wikipedia had to say about it: Roman infantry tactics - Wikipedia
 
Mar 2018
523
UK
#4
Pushing power is mostly psychological. It's harder to turn away and run when there's 30 people behind you. It also gives you the ability to rotate tired men/centuries/formations from the front line and the reserves. Lastly there's the physical constraints of the battlefield, you can't make your line arbitrarily long, and controlling such a formation without modern communication would be extremely difficult. It's easier to peel off a reserve from a deep formation to lengthen it than to do the reverse!

But most of all, almost every army was deployed longer than deep! A standard consular roman army of 2 legions deployed in the triplex axies would be 360 men wide and 24 men deep (It's actually more complicated than that if you include light infantry and cavalry, and there breaks both in the width and then depth, but that's the total number of legionaries in each rank and file). That's far wider than it is deep! And the Romans were those who used a deep formation the most.
 

Chlodio

Ad Honorem
Aug 2016
3,485
Dispargum
#6
If one planned to fight defensively, it was usually a good idea to find two terrain features on the battlefield to anchor your flanks, then fill in all of the empty space between them. Length and depth was therefore determined by how many men you had and how far apart those two terrain features were.

If planning to attack, it was often a good idea to line your units* up one behind the other and hit the enemy line like a huge battering ram with the intention to shatter the defensive line.

*units being a more modern term. Not all ancient and medieval armies were organized into standard-sized units in the modern or Roman sense.


You're right, sometimes going too deep overly restricted an army's ability to maneuver or react to unexpected events. But, "It seemed like a good idea at the time" probably applies to many instances. The general who was defeated by an overly deep formation may have planned to fight a completely different battle but lost control of events.
 
Jan 2015
2,813
MD, USA
#7
The thebian strategy of going deep on one of their columns worked in their war against the Spartans after the peloponessian war
Did it? At Leuktra, the Spartans were in the middle of extending their phalanx to the right in order to outflank the Thebans when their own cavalry retreated in disorder and disrupted the phalanx. THEN they were hit by the Theban infantry, apparently including the 50-deep phalanx (though only the Sacred Band is specifically mentioned). At that point "a furious fight broke out". The Spartans did NOT break instantly, nor were they swept from the battlefield. It sounds like they stopped that Theban column cold, in spite of being overextended and disordered.

I strongly suspect the deep Theban phalanx was designed to counter an outflanking wheel by the Spartan right, it which case it just might have worked. Hopefully it wasn't designed to punch through the Spartan line like a battering ram, because it seems to have failed at that.

I tend to agree that deep formations have their use, but are not (and *were* not) automatically assumed to be better at punching through an enemy line, nor for simply adding more weight to the "push". But getting definite answers may be impossible without training several armies to try killing each other with historical weapons, and experimenting with various formations and concepts. We *can* learn a lot from reenactments, riot police actions, the mechanisms of moving crowds, etc., but without the same lethal intent as an ancient battle, our conclusions must be cautious at best.

Matthew
 
Feb 2018
189
US
#8
A breach in the formation that an enemy could exploit was something to prevent at all costs. Cohesive formations likely gave an enormous psychological and physical bonus. The longer the formation, the more unwieldy it can be, and the more likely a gap will arise just from something as simple as units marching forward at different speeds due to differing enemy pressure or the roughness of ground they have to cover. At Gaugamela, Alexander the Great was able to puncture the far superior Persian army as it lengthened to try to flank his right, and that break led to its destruction. At Paraitakene, Antigonus hit a vulnerable hinge in between Eumenes's center and wing during the chaos of battle that turned a severe defeat into only a moderate loss/draw.
 
Sep 2017
610
United States
#9
Not saying that Total War is anywhere close to an accurate representation of ancient warfare, but I've been working wonders in multiplayer in Rome 2 putting my forces into a triple line rather than one extended line.

Why? Because of reserves.

I can send detachments around the flank of my enemy, guard against flanking attacks, and reinforce my battle line if the front rank is broken. I've only had two foes successfully deal with it, one of them also using a multi-line approach as opposed to the more common enveloping tactic.

That's probably the most critical part; if a long, but thin line breaks anywhere, then it's pretty much game over as the men swarm in the breech and split the army in half. In battle, the frontline troops are likely to get battered, tired, and demoralized. While ideally you can swap them out in lulls in the fighting, if they do break, there's men behind them who can fill in the gap and prevent the army from being split. And, they are less likely to break if there's a large amount of men behind them.
 
#10
Going deep gives you one big advantage: reserves. Even if your front line gets broken, there is another line of infantry step up and stabilize the situation. If you have only one line, then, generally, once that line gets broken, the whole army routs. Also, your 2nd and third line troops are rested, and if need be, they can be peeled off and respond to developments on the battlefield, like at Pharsalus.

Romans used triplex acies for centuries. Clearly it had something going for it. Here's what Wikipedia had to say about it: Roman infantry tactics - Wikipedia
Right, but wouldn't it be wiser to have your reserves farther back so they can respond to needed areas better? While at the same time not inadvertently squeezing your own troops and lessening the risk of envelopment?
 

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