How did soldiers communicate with the Leaders of the army
The Germans used dogs to carry messages to certain location. They preferred breeds that were smart and easy to train.
Pigeons where used to carry messages in WWI. Pigeons could be killed by a hawk. But it was close to impossible for a marksman to shoot a pigeon in WWI.
Americans would send messages in Choctaw so the Germans couldn't decipher it.
They would also use telephones connected with one giant wire.
The British used simpler communication devices like the telegraph.