As Big Ben strikes the 11th hour this Remembrance Day, for the first time no veteran of the first world war will hear it; remembrance has become history. Yet if the men are gone, their stories live on, and new ones are still emerging. Jack Martin’s war diary was ­doubly secret. Concealed during his service (soldiers were forbidden to keep diaries), it remained hidden until long after his death.

He enlisted in 1916 and became a signaller in the Royal Engineers, a unit that played an often overlooked but vital part in the new “industrial warfare”. Already 31, cultured, ­literate, a gifted pianist and a keen amateur astronomer, Martin was a “reluctant, idiosyncratic soldier” and a far from typical “other rank”. He spent cloudless evenings in the lines teaching his comrades the names of the stars and constellations. To them he may have appeared clipped and unemotional — a stereotype of the clerk he had been before the war — and his first diary entries were as terse and factual as accounts in a ledger, but they grew increasingly revealing in the face of trench warfare.

Martin’s only physical injury was a “cat’s claw” shrapnel scratch, but he suffered shell shock and saw action in the Somme, ­Messines Ridge, Ypres and the last great German offensive in spring 1918. He became sufficiently hardened to confront war’s ­horrors “without a shudder”, but his moral compass never wavered. He condemned the mind-set that saw comrades punished for minor offences by being “tied up like slaves”, adding that “Prussianism is not confined to the Germans”, and described the attempts of a newly arrived “blood-red major” to stir bloodlust in his men as “utterly disgusting”: “I am sorry to think that England should consider such a thing necessary.”

Honest, insightful and full of humour, he also developed an eye for the absurd, such as the Guards officer with six wound stripes, who always rested his arm on the side of his car “for display purposes”, and the officer who sentenced his dog to “Field Punishment No 1” for absence without leave, having it tied to a tree and fed on biscuits and water.

There are vivid depictions of the Goya-esque horrors of war — the flesh-creeping wait for an enemy attack, the “bite and sting” of shellfire — but also lyrical descriptions of his unit’s “Elizabethan progress” through northern Italy, the play of light on the Alps and, after the ceaseless rumble of the guns on the western front, the “uncanny and almost palpable silence of the trenches in the mountains”. Even more touching is his record of attempts at a semblance of domesticity even in the depths of war: fresh flowers placed in a polished shell case inside his dugout, scraps of torn fabric as a tablecloth.

At the end of the war, Martin returned home, married his fiancée and, self-taught in law and accountancy (he had been too poor to go to university before the war), set up an accountancy practice, in which his son, Peter, their only child, eventually became a partner. Although his war experiences must have scarred him, Martin found ways to distance himself from them. Even his medals ­disappeared; Peter believed that his father probably threw them away. Like so many other veterans, Martin never spoke about the war. After his death in 1970, aged 85, his testament was almost lost forever. Bundled into a black plastic bin bag, the diaries remained in the attic of the family house in London for another 30 years until Peter found and read them. Richard van Emden’s editing of the diaries is sensibly unobtrusive and self-effacing, largely allowing Martin’s words to speak for themselves.

Sapper Martin edited by Richard van Emden
Bloomsbury £18.99 pp288

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