author
A young French officer’s wartime diary became a vivid firsthand account of life at the front in 1915. Published in English as Campaign Diary of a French Officer, it stands out for its direct, unsentimental view of marching, trench duty, bombardment, and recovery after being wounded.

by Lieutenant René Nicolas
Very little biographical information about this author appears to be widely documented in the sources I could confirm. He is identified in library and public-domain editions simply as Lieutenant René Nicolas, a French officer whose diary covers the period from February to June 1915 during World War I.
His best-known work is Carnet de campagne d'un officier français, later published in English as Campaign Diary of a French Officer. Library of Congress records note that the work first appeared in The Atlantic Monthly in 1917 under the title The Lieutenant's Story, and was then issued in book form by Houghton Mifflin the same year.
Because the surviving records I found focus mainly on the book rather than the man himself, it is safest to remember him through his writing: a concise, firsthand chronicle of a French soldier’s experience on the Western Front, valued for its immediacy and plainspoken honesty.