Delvert's first book, Quelque héros (Paris: Berger-Levrault), was published in November 1917. It is simply a collection of factual accounts of gallantry at the front. Occasionally the author's experiences emerge, but all material that will appear in his later books. Perhaps it was Delvert simply dipping his toe in the water of publishing. Nonetheless, it went through at least six editions within a year.
Delvert had always kept a diary, and it is these notebooks that form the basis for his most important works. The first was Histoire d'une compagnie: Main de Massiges - Verdun: novembre 1915-juin 1916: journal de marche (Paris: Berger-Levrault), published in July 1918.
In December 1920, Delvert used his diaries from his time on the staff of 5th Army to write L'erreur du 16 avril 1917 (Paris: L. Fournier). It was this army that took one of the major parts in the disastrous Chemin des Dames offensive. On the opening day, Delvert was able to observe the progress of the attack (or, rather, non-progress) from XXXII Corps' position at Point 186, west of Cormicy.
In January 1921, Delvert provided the text to accompany fifty-nine reproductions of paintings by Joseph-Félix Bouchor, published as Verdun (Paris: L. Fournier). Again, there was little personal in the text, although it did include a section on the defence of redoubt R1, in which the 101st took part.
Delvert then temporarily abandoned military history. His next published work was actually a speech given at a prize-giving at the Lycée d'Amiens in 1924: 
Discours prononcé par M. Charles Delvert, professeur agrégé d'histoire, à la distribution des prix, le samedi 12 juillet 1924, sous la présidence de M. Armand Tumel, avocat, président de l'Association des anciens élèves (Amiens: imprimerie du Progrès de la Somme).
Discours prononcé par M. Charles Delvert, professeur agrégé d'histoire, à la distribution des prix, le samedi 12 juillet 1924, sous la présidence de M. Armand Tumel, avocat, président de l'Association des anciens élèves (Amiens: imprimerie du Progrès de la Somme).
He used his trip around the world to inform his next book L'Algérie (Paris: Hachette), published in July 1930.
In October of the same year, he published another work of history, a school textbook intended for baccalauréat students - Memento. Histoire contemporaine depuis le milieu du XIXe siècle (1848-1920) (Paris: Emile Croville.
For his final major work, he returned to his wartime diaries. Carnets d'un fantassin was published in 1935 (Paris: Albin Michel). It covered his service from the outbreak of war until August 1916, and so overlaps his first book. It has been through several subsequent editions, in 1966, 1981, 2003, 2008 and 2013 - all in French, so my translation will be the first in English.
The cover illustrations are taken from the websites of assorted dealers.
The cover illustrations are taken from the websites of assorted dealers.