Just stumbled over this fascinating BBC documentary. Well worth watching for those who haven't seen it.https://www.youtube.com/watch?v=KtmDJUI06wg
It uses as it's base a 78 minute film made in 1919 when Jacques Trolley de Prévaux and his cameraman, Lucien Le Saint, flew an Astra dirigible from Nieuport on the Belgium coast to Verdun.
The documentary is striking in it's content, using snippets from the above film to illustrate just how widespread and devastating to the land the war was. And how well over time things got back to normal.
More importantly, from a gamers POV, is the excellent detail contained in de Prévaux's film. The trench lines, the critical importance of aerial reconnaissance (the most important aspect of the air war IMHO), the devastation to the land, the ruined cities. All good for creating greater detail for the sim.