Re: Canon de 155 L Modèle 1877 and Canon de 120mm Mle1878
Would also add to these excellent suggestions the canon de 105mm Schneider Mle 1913 which served not only in WW1 but was also the principal gun of the French Army in 1940. It was exported widely between the wars to Poland, Yugoslavia and Czechoslovakia and Belgium.
This Gun was originally designed for the Russian Army by Schneider as the Putilov(built by)107mm M10, adopted by the French as the Schneider 105L M13 TR, and in Italy as the Ansaldo(built) 105/28 M13...
Not to forget guns supplied to other nationalitys which were numerous, what should be remembered though is many underwent motorised conversion bettween the wars but this can be done with a different set of wheels supplied for that version.
What about generic supply troops that could we used for most troops ?
Including pack animals with interchangeable loads,the troops could be carrying boxes containers sacks poles etc
Even generic medical would be useful