There was a perfect web of them, reaching all the way from Alsace and the Forest of Argonne to the sea.

Generals talked to one another over them, and over these wires the signal officers sent messages to the men in the batteries telling them how to fire their guns.
The telegraph, too, was at work.

The wires were clicking everywhere, and the air was filled also with messages which went on no wires at all, but which took invisible wings unto themselves.

The wireless, despite its constant use, remained a mystery and wonder to John.

One of his most vivid memories was that night on the roof of the chateau, when Wharton talked through space to the German generals, and learned their plans.
He looked up now and his eyes were shut, but he almost fancied that he could see the words passing in clouds over his head, written on nothing, but there, nevertheless, the most mysterious and, in some ways, the most powerful part of the hosts of the air, the hosts that within a generation had changed the ways of armies and battles.