I've seen advertisements showing railroad flatcars carrying model tanks lately. But who makes them, and which ones would be suited for the Great War era?
If you have a look at my post on the Locomotives at Cambrai thread (landships.activeboard.com/t64468550/locomotives-at-cambrai/) I list the three primary wagons in both HO and OO scales. Note that the Parrot/Warflat wagon was also produced for the US Army during WW1.