How did they tell each other apart?

[Yehya]

At the battle of Pharsalus the two legions on Pompey’s left had been recently sent by Caesar to the senate and were opposed by, I think, the VII and X legions. Assuming equipment was basically the same how did they tell who was who when they slammed together and mixed up?

[Crispianus]

Its curious you should ask this as although I dont know what the Romans did for identification in battle, I read yesterday in Xenophons Anabasis that the Greeks at Cunaxa had a password of sorts:

Xen. Anab. 1.8.16
"Xenophon replied that the watchword was now passing along for the second time. And Cyrus wondered who had given it out, and asked what the watchword was. Xenophon replied “Zeus Saviour and Victory.” "

[MonsGraupius]

At the battle of Pharsalus the two legions on Pompey’s left had been recently sent by Caesar to the senate and were opposed by, I think, the VII and X legions. Assuming equipment was basically the same how did they tell who was who when they slammed together and mixed up?

The same question applies to schoolkids playing football. Or even Chimpanzee troops engaging in territorial conflict. 7million years of humans who were dumb enough to get lost in battle and end up in the territory of the "other side" tended to die out fairly rapidly.

[Yehya]

School kids used to do “shirts vs skins” to tell them apart. Or they wear different colors, or flags. I seem to remember one side tying a white cloth to one arm but I don’t have source material

I suppose it could which way your facing but how do you tell a fleeing enemy Roman legionary from one of your own guys chasing him if all you can see is his back? Auxiliaries I can see they often wore different armor and clothes but two Roman legions? There must have been something

[Nathan Ross]

how did they tell who was who when they slammed together and mixed up?

A problem for armies throughout history, until the development of uniforms in the 17th-18th century!

Different units apparently had different shield designs, which might provide some distinction; there's the famous story from the civil war of AD69 of two men from one side taking shields from the enemy dead and using them to infiltrate the opposing lines and disable a ballista.

Alternatively, Romans could have done what other armies did and used some sort of distinguising mark - an armband perhaps, as you suggested, or a crest. I've long believed that the 'horns' shown on the helmets of the men on the Arch of Constantine might have been twin feathers worn on the helmet as an identifier by Constantine's Gallic troops - particularly useful in a civil war in which detachments of the same legions might have been fighting on opposing sides!

[Dan Howard]

Battles weren't like schoolkids playing football or a Hollywood movie. Anyone who wanted to survive stayed in formation so it was easy to tell who the enemy was - everyone who wasn't facing the same direction as you. If the formation broke down then you had a lot more serious problems than trying to work out who the enemy was.

[MonsGraupius]

Battles weren't like schoolkids playing football or a Hollywood movie. Anyone who wanted to survive stayed in formation so it was easy to tell who the enemy was - everyone who wasn't facing the same direction as you. If the formation broke down then you had a lot more serious problems than trying to work out who the enemy was.

I read a very good description of an early moden African battle. The two sides would line up and then advance toward spear throwing distance. One side would then throw the spears, whilst the other defended with their shields. then the other. This was repeated till the spears were exhausted, and then one or other or both would retreat. Rarely would the two sides actually close in on each other. So, in such combat, there really isn't a problem knowing who is on which side.

But when armies started close combat problems started. But I heard one description suggesting that battles were fought in very short bursts. That may well have been because as soon as the ranks became disorganised - so that a soldier could not know who was about them, troops naturally retreated back to their lines.

So, as armies moved more to closer combat, i would imagine, from standing at spear throwing distance, they would then rush forward, perhaps in smallish family or village groups who knew each other, engage for a minute or two and then rush back. But, once one group pushes forward, those remaining back would watch to see if the attack provided any further opportunity to rush forward where troops were otherwise occupied. The net effect might be that we see "Mexican waves" of attacks, starting at one point - then encouraging those to the side to rush forward, then along the "line", but then the first group retreats, and that initiates a wave of retreat. Only later in the evolution of armies, would they start to attack en masse.

And, one of the hallmarks of a successful army would be the ability to maintain order (i.e. know who is fighting next to you) in the heat of battle. That is because the longer a troop of soldiers knows it has its comrades to left or right, the longer it can fight before retreating. However, that implies one of the ways to terrify an enemy, is to confuse them about who is on their side. The quicker troops lose confidence that they are surrounded by their own side, the quicker they retreat.

So, in a conflict between two identically dressed groups, the more ordered/disciplined group would have a huge advantage.

[Mark Hygate]

Battles weren't like schoolkids playing football or a Hollywood movie. Anyone who wanted to survive stayed in formation so it was easy to tell who the enemy was - everyone who wasn't facing the same direction as you. If the formation broke down then you had a lot more serious problems than trying to work out who the enemy was.

One of the most intelligent things I've seen written recently...

What most people don't fully realise, given books gloss over it and 'Hollywood' cannot afford the delay before the next 'instant gratification' moment; is that most battles take inordinate amounts of time.

Ancient armies camped near each other, perhaps skirmished a little over access to resources.  After breakfast they might deploy and offer battle, which may not have come that day!  The whole day could be spent in gentle manoevering, a bit of skirmishing here and there; actual contact fighting occupying a small proportion of the time, if any.  The entire thrust of a battle being to disrupt the enemy's formation/line, for once that happens then it's nearly always over.  The often disproportionate loss rates between the victor and the vanquished are all to do with the hunting down of the fleeing troops and the much smaller losses that happened in actual melee.

Even today, a common military adage remains 'hurry up and wait' - I very much believe that not much has changed.

[dadlamassu]

Ancient armies tended to draw up their battle lines in standard, predictable ways. So the formations in a Roman Civil War probably drew up in the same way as each other. After the auguries taken and found favourable, a bit of skirmishing might precede the advance to contact by the main lines. Salvos of pila exchanged as the lines meet and a shoving and stabbing match of 6, 8 or more ranks deep takes place. It continues until one side starts to run away. This would likely be slow to start with. Perhaps a cohort or two gets exhausted and starts to give ground. The other side pushes harder, crosses the tide line of bodies increasing the pressure as the enemy rear ranks give way. Other units looking left and right see this. Some start to give ground or are steadied by their Centurions and Optios or maybe the arrival of the General or other senior officer.
Largely, I imagine that the area of battle that a soldier can actually see is very small just a few men on each side of him and he probably knows everyone he can see in his unit. When he cannot see his mates because strange chaps are going past him it is time to get worried! The formation is breaking up and battle drills are failing to close gaps. The killing really starts as one side flees and the cavalry and light infantry chase them down.

[Graham Sumner]

Equally important is how did they all tell each other apart when not in battledress but were just wearing cloaks and tunics. You can read my take on this in:

'Roman Soldiers: Fashion icons or military elite'. in ‘Egypt as a Textile Hub: Textile interrelationships in the 1st millennium AD’. Ed. A. de Moor C. Fluck & P. Linscheid. Tilt Belgium 2019.

This comes with lots of illustrations and reconstruction paintings. However if you are just interested in the latter then they will also appear in a forthcoming book but without all the sources.