Use of whistles to relay commands in battle

[Crispvs]

I may be mistaken in this, but doesn't the detail of exchanging lines to put fresh soldiers in the front line come from Polybius, meaning that it is a practice of the second century BC and one which may not have been in use later, useful as it might seem. Caesar, nearly a century later, on one occasion mentions deciding to put his men into the the traditional three line formation, which recalls Polibius' description but at the same time suggests that other formations (and possibly practices) were in use by this time. What that might mean for formations a century after this is anyone's guess.

Regarding the actual practice of exchanging men, I would prefer to try and build a reconstruction of how it might be done on the basis of things we already know rather than things which are little more than theory. To witt: we know the Roman army used trumpets; we know they could be formed into three lines, the front two of which could in some way be exchanged; we know they had large numbers of projectile weapons in the form of pila and probably slings and arrows; as well as knowing that they trained intensively (which was probably the case in Polybius' time as well, at least during periods of service).

Using these factors I would propose the following as a possibility for Caesar's time, using one cohort of 480 men as my example:

The three maniples are stood next to each other, with prior centuries in open order in front, posterior centuries in closed order behind. I assume the frontage to be ten men for each century/maniple, with the most experienced and best equipped men in the front two ranks.
During the fighting the front thirty men do the bulk of the fighting. As they are more experienced and better equipped they stand far more chance of surviving than many of the more inexperienced and more poorly equipped men behind them, who are there largely to give the formation depth and staying power if the enemy try to push forward. Some of the men in ranks three four and five might throw javelins over the heads of the men in front from time to time if space was available and they were not tightly compacted. Those in ranks six, seven and eight (assuming an eight man depth) could not do so due to the possibility of hitting their own men. Any serious casualties in the front rank would be replaced by experienced well equipped men from the second rank, with the wounded men being withdrawn from the front line in an ad hoc but well practice way. Men who had fallen might be able to be dragged back by men in ranks behind, as is described several times in the Iliad (which of course might not be relevant as it describes warfare several centuries before).

After a given time (perhaps five minutes) the posterior centuries replace the now tired prior centuries. At a signal from a trumpet, the front ranks of the prior centuries intensify their efforts for a short burst which which cannot be sustained for long but which drives the enemy back slightly, allowing the prior centuries to contract into closed order. This would start in the rear ranks , allowing the posterior centuries to move forward through the gaps being created by the contracting prior centuries. As the posterior centuries move forward the contracted rear ranks of the prior centuries begin to fall back, allowing the posterior centuries to begin to expand towards open order. By this stage the prior and posterior centuries would look like interlocking triangles from above. As the middle ranks of the prior centuries contract, the still contracted front ranks of the posterior centuries rapidly move forward between them and release a volley of pila over the heads of the still expanded front ranks of the prior centuries, causing a momentary confusion in the enemy ranks which allows the front ranks of the prior centuries to contract and withdraw while the front ranks of the posterior centuries move forward and expand into open order. With a frontage per century of only ten men, the expansion to open order would take only a second or two, giving a new cohort frontage of thirty fresh well equipped men. While this was going on the middle ranks would throw a further volley over the head of the men in front to cause more discomfort to the enemy while the front line was compromised. As the contracted front ranks of the prior centuries withdraw, the ranks of the posterior centuries would fully expand to open order, closing the gaps between the centuries again to produce a cohesive thirty man wide, eight man deep formation.

I think that with a few days' training, such an operation would be relatively easy to achieve and would possibly take about a minute to carry out.

Meanwhile the three prior centuries would draw back a little way to spend five minutes catching their breath and sorting themselves out, before exchanging back to the front again.

I don't think that many trumpet blasts would be required to carry out this operation once the men were used to doing it.

I appreciate that this suggestion is far from perfect, but I offer it as what I hope is a more realistic suggestion than the HBO idea.

Note that I do not think that the exchange of lines refers to an exchange of individual ranks but of full lines several men deep. Also, regarding the idea that you could put a hand around a belt to pull a man back, I think that if a weighted belt is loose enough to fit your hand behind, it is also loose enough to start slipping down.

Crispvs