Battlefield signalling

[Dangun]

I am getting a little confused.
What are we suggesting - in this discussion - when we use the word "signal"? Are we suggesting the signal is visual (waving a flag), or aural (sounding a horn), or either.

Sometimes the sources are precise "ordered the signal to be sounded" (Gallic War 7.46). Most of the time they are not.
Similarly, if a source says "signal" but not "order" is it being used to differentiate or synonymously?

If signals were visual, it seems odd that we never get a better description of them.

[Erpingham]

I am getting a little confused.
What are we suggesting - in this discussion - when we use the word "signal"? Are we suggesting the signal is visual (waving a flag), or aural (sounding a horn), or either.

We appear to be talking about both visual and sound signals.  The latter seem most common.  We have muddied the waters by moving onto other ways of communicating on battlefields, such as shouting or sending messages.

Other than a hint from Duncan (I think) about Chinese signalling, we haven't turned up much evidence of a complicated "signal book" at unit level - mostly we are talking fairly broad commands at higher level with the occassional "special" .

[Patrick Waterson]

What are we suggesting - in this discussion - when we use the word "signal"? Are we suggesting the signal is visual (waving a flag), or aural (sounding a horn), or either.

Sometimes the sources are precise "ordered the signal to be sounded" (Gallic War 7.46). Most of the time they are not.
Similarly, if a source says "signal" but not "order" is it being used to differentiate or synonymously?

In this context, a 'signal' is a cue to execute an 'order'.  The order is prearranged, either through it being part of usual tactical procedure, e.g. going on to the attack (and what you do when you go on the attack) or by a pre-battle briefing ("When you see a red flag hoisted on this hill you will charge") or through it being a standard army procedure (general advance, general retirement, general halt).  The signal is the audial and/or visual cue to execute the order.

Giving new orders to a unit or command seems to have involved the direct intervention of the C-in-C.  One example of an order change in mid-battle is Claudius Nero on the Roman right at the Metaurus in 207 BC.  His wing of crack troops were getting nowhere in their attempts to scramble up unforgiving terrain in the face of Hasdrubal's Gauls, so he decided to switch some of them them to the Roman left by a march around the rear of Livius Salinator's army, which was engaged with Hasdrubal's Iberians.

"Claudius shouted to his soldiers, "Why then have we covered so long a march at headlong speed?" and endeavoured without success to lead his line up the hill. [13] Thereupon, after discovering that they could not get to the enemy in that direction, he drew off a number of cohorts from the right wing, where he saw that they would be standing idly by instead of fighting. [14] He led them round behind the battle-line, and to the surprise not only of the enemy, but also of his own side, charged into the enemy's right flank. And such was his speed that, soon after showing themselves on the flank, they were already attacking the rear." - Livy XXVII.48.12-14

Note how the C-in-C (of that particular wing of the army) personally 'drew off a number of cohorts' and personally led them round behind Livius Salinator's army to assail Hasdrubal's right flank and rear.  This kind of personal intervention by the C-in-C may have been par for the course for a change of orders in classical times: anyone is welcome to quote instances of this or other mid-battle order changes so we can examine this aspect.

[Dangun]

In this context, a 'signal' is a cue to execute an 'order'.  The order is prearranged, either through it being part of usual tactical procedure, e.g. going on to the attack (and what you do when you go on the attack) or by a pre-battle briefing ("When you see a red flag hoisted on this hill you will charge") or through it being a standard army procedure (general advance, general retirement, general halt).  The signal is the audial and/or visual cue to execute the order.

That is of course very coherent.
And in this case of Gallic Wars 7.47 it is really clear.
But I am not sure we can always rely on the texts differentiating these meanings as precisely as the forum particpants do.

Even later in  the same paragraph, we see that some orders have signals but some orders are just orders.

Caesar, having accomplished the object which he had in view, ordered the signal to be sounded for a retreat; and the soldiers of the tenth legion, by which he was then accompanied, halted. But the soldiers of the other legions, not hearing the sound of the trumpet, because there was a very large valley between them, were however kept back by the tribunes of the soldiers and the lieutenants, according to Caesar's orders;

Ever-doubtful, this paragraph looks a bit off to me, because if Caesar's orders halted the other legions, why did he have to blow a signal to halt the legion he was accompanying? Hadn't the tribunes received the same orders/briefing. Its odd to have to make an extra effort to stop the troops closest to you.

I suspect the "according to Caesar's orders" in the last line is a casual hagiographical addition, when in reality it might have been standard operating procedure by the leaders of the other legions.

[Patrick Waterson]

Caesar, having accomplished the object which he had in view, ordered the signal to be sounded for a retreat; and the soldiers of the tenth legion, by which he was then accompanied, halted. But the soldiers of the other legions, not hearing the sound of the trumpet, because there was a very large valley between them, were however kept back by the tribunes of the soldiers and the lieutenants, according to Caesar's orders;

Ever-doubtful, this paragraph looks a bit off to me, because if Caesar's orders halted the other legions, why did he have to blow a signal to halt the legion he was accompanying? Hadn't the tribunes received the same orders/briefing. Its odd to have to make an extra effort to stop the troops closest to you.

I suspect the "according to Caesar's orders" in the last line is a casual hagiographical addition, when in reality it might have been standard operating procedure by the leaders of the other legions.

Caesar's 'orders' (praeceptum = maxim, principle) in this case were not battlefield orders but standard operating procedure: his officers were apparently acting on his general principles (do not let the men loose unless Julius signals it).  The officers were trying to keep the men back but the troops were having none of it: they went on anyway, having not heard the recall signal which the Tenth had heard and obeyed.  That is all Caesar is saying here.

[valentinianvictor]

Ammianus gives accounts of various battles where signals were mentioned during the course of the battle. The battle always appears to start at the signal given by 'trumpets'.