Artillery Observers

2017_03_07

After all this lightweight and heavyweight artillery demonstration, time to observe! Of course, You could have done this before, and maybe You wouldn’t have lost so many units, but it’s never too late to start.
We didn’t start the war with trained meerkats, so You will have to use the available Russian artillery Observer or the KuK artillery Observer.

What objects would You use nowadays for observing during a war? What was available during the Great War?