Which one of these guys were you???

That must be me down in the lower right, taking down all the stuff the Observer and the Dit were telling me and ZAG'in it off to "Big Daddy"...or, in this case, strapping it to the leg of a carrier pigeon.
  "ZAG": A "Z-Signal" meaning "TRANSMIT".

I guess the Signal Corp couldn't afford an airplane during WW1, they had to stand on top of caisons for the best view of the enemy.

But, what's funny is, the equipment the "Dit" has looks pretty much the same a I remember them having in 1970.

That pole running up the right hand side of the picture, just has to be their antennae field.