Estienne described it as 'magisterial' and in many respects it is an unoffical AS History, the AS being the Artillerie Speciale - the French tank arm. (Indeed, the post-war internal AS history appears to have made good use of Dutil's work for its own composition, see these papers in SHD 16 N 2120.) Its a very interesting book which covers in depth the arguments between Estienne and the various political departments that were connected with the AS, as well as extensive discussions on tank manufacture and design. The various tank battles are not dealt with in as much depth as you will find in Perre's work and the maps in the pdf aren't as good (being reduced) as in the original. While I can't claim to have checked every item in Dutil with the archive sources at Vincennes, I haven't found any substantial errors when cross-checking the archive sources. As he say in the introduction, 'I was there.' I haven't checked his service record yet but I believe that he was with the AS from at least late 1916 to the end of the war. It is in French but you can get a great deal of material out of it with very basic French. Enjoy!