Communications:

There's a photo of a British World War 1 tank, probably a Mark IV, I'm sure you can find it ... There's a hand reaching out through a little port on the back (I assume) letting go of a passenger pigeon.

In World War 2, German tanks had really underpowered AM radios with limited range and, of course, full of static from every electrical circuit in the tank. Moreover (!) most of them were only receivers. Only the command tanks could transmit. You get it...

US Shermans, though, had higher powered Motorola (are you ready?) FM transceivers. Static free.

Armies may still march on their stomachs, but they win on comms.