A commentator on the Angry Staff Officer’s blog introduced me to Major Digby Tatham-Warter (d. 1993):
A Company was then chosen by the battalion’s commanding officer, Lieutenant Colonel John Dutton Frost, to lead the 2nd Parachute Battalion in the Battle of Arnhem, part of Operation Market Garden, because of Digby’s reputation of being an aggressive commander. In preparation Digby, concerned about the unreliability of radios, educated his men on how to use bugle calls that had been used during the Napoleonic Wars for communication in case the radios failed. He also took an umbrella with his kit as a means of identification because he had trouble remembering passwords and felt that anyone who saw him with it would think that “only a bloody fool of an Englishman” would carry an umbrella into battle.
A Company were dropped away from the target of Arnhem Bridge and had to go through Arnhem where the streets were blocked by German forces. Digby led his men through the back gardens of nearby houses instead of attempting to advance through the streets and thus avoided the Germans. Digby and A Company managed to travel 8 miles in 7 hours while also taking prisoner 150 German soldiers including members of the SS. … Digby was later injured by shrapnel, which also cut open the rear of his trousers but continued to fight until A Company had run out of ammunition. Despite the radios being unreliable as Digby had predicted and the bugle calls being used most in the battle, the message “out of ammo, God save The King” was radioed out before Digby was captured.
Now, that story makes me think of lots of things, but one of them was another piece of soporific prose about an exciting subject:
[We shall, furthermore, train the army to distinguish sharply the commands] given sometimes by the voice, sometimes by visible signals, and sometimes by the bugle. The most distinct commands are those given by the voice, but they may not carry at all times because of the clash of arms or heavy gusts of wind; less affected by uproar are the commands given by signals; but even these may be interfered with now and then by the sun’s glare, thick fog and dust, or heavy rain. One cannot, therefore, find signals, to which the phalanx has been accustomed, suitable for every circumstance that arises, but now and then new signals must be found to meet the situation; but it is hardly likely that all the difficulties appear at the same time, so that a command will be indistinguishable both by bugle, voice, and signal.
– Asclepiodotus, Tactica 12.10 (very similar passages appear in Aelian and Arrian but tracking them down is too much work for a blog post)
Some scholars are indignant that although we have three surviving manuals on Hellenistic tactics, they are all concise, academic paraphrases of one or two common sources, sources which were probably also written by armchair scholars who had read the works of fighting soldiers like Pyrrhus of Epirus and Polybius. It is true that these manuals describe an ideal army, not an army which actually existed at a particular place and time: their purpose is to give a general idea of how a Macedonian phalanx worked. But they also contain plenty of excellent practical advice, which can be learned painfully and dangerously through experience or safely and comfortably from books and adventurous friends.
In this case, the lesson is “any one method of communications can and will fail, so prepare several and be ready to improvise.” You can phrase it like that, or more colourfully in Murphy’s Laws of Combat, or in business-speak in warnings about the danger of showing up to a presentation with your slides in a format which the local computer can’t read, but it is a very useful principle.
As Asclepioditus also says: “These are in brief the principles of the tactician; they mean safety to those who follow them and danger to those who disobey.” Being caught unprepared in combat when your communications fail is much more dangerous than being caught unprepared when your one alarm fails to go off before an early-morning flight.