What would actual use case for this look like? The post mentions communication, but the usefulness of laying communication lines behind enemy lines seems like it would be minimal. Lines would be easily discovered and would lead right back to the spy or scout. The other use could be for demolition which I could see, but if I were a saboteur I would just twist the lines together as it's very temporary and time is of the essence.
Back in WW2 many communication lines were a single wire with an earth return ... years ago I was told a story (by people who were old enough to have been there) of doing that in the desert when they were facing Rommel .... guy picks up the phone, winds the generator to make it ring at the other end, someone picks up the phone answers "jawohl" .... sudden silence on the kiwi end, followed by scurrying around to find someone who spoke german so they could listen in.
Of course what had happened was that there were two parallel earth return phone lines on either side of the front, the lowest impedance path used both .....
Now this story was told to me by some old timers (people who could talk to you at the same time as they held a conversation in morse) - they told some great stories (all that I know of were true) - take it with the appropriate grain of salt
These were usually used at the front lines, to communicate with people stationed a little further back. Radio signals can be detected and eavesdropped, especially in WWII days.
It's not well-known, but the British tracked the Germans down to the unit level using radio transmission triangulation, and plotted their positions across Europe on giant maps. Even without decrypting signals, they knew a great deal.
The Germans were the first army to have radio on every vehicle, sometimes 3 for higher ranks. It was handy on the go, but leaked intelligence like a sieve when stationary for days, and the Germans were overconfident in its secrecy.
The British were warned of air raids even before takeoff because German pilots followed a procedure of testing their radio on the ground.
The mastermind behind the British effort built a similar system, but global, for the US, after WW2.
SR-71 flights initially used radios, but since Russian "trawlers" were tracking the broadcasts, later flights, including multiple refuelings, were done in radio silence.
