Like nearly every other male writer in English to have tackled the subject of war, Mr. O’Brien owes a clear debt to Hemingway, who came as close to anyone to striking a template for how it should be dealt with in a famous passage from “A Farewell to Arms”:

“There were many words that you could not stand to hear and finally only the names of places had dignity. Certain numbers were the same way and certain dates and these with the names of the places were all you could say and have them mean anything. Abstract words such as glory, honor, courage, or hallow were obscene beside the concrete names of villages, the numbers of roads, the names of rivers, the numbers of regiments and the dates.”

Image A 1918 United States Tank Corps recruitment poster. Credit... The Huntington Library

This tough wisdom — itself curiously abstract, in spite of its insistence on specificity — has remained in effect even as the geography has changed. The imperative to tell what really happened, even to a public or a posterity incapable of fully understanding, has produced a literature full of names and dates. Verdun, Passchendaele, Gallipoli, Guadalcanal, Monte Cassino, Stalingrad, Inchon, Khe Sanh, Kandahar, Fallujah. Nov. 11; June 6; Tet; Sept. 11.

In 1964, 50 years after the war began, Philip Larkin, born in 1922, published a memorial poem called “MCMXIV.” Larkin’s subject is less the war as such than a faded England of “archaic faces” and bygone habits, an England that ceased to exist sometime between the assassination of Archduke Franz Ferdinand in Sarajevo on June 28 and the commencement of full, continent-engulfing hostilities at the beginning of August. The poem tries to freeze the moment when the older world — a world his parents knew intimately but one that lay just beyond the horizon of his own memory — “changed itself to past without a word.”

“Never such innocence again,” Larkin concludes, summarizing what was, then and now, a crucial tenet of the conventional wisdom about the Great War, a notion that informed Hemingway’s rejection of the old, elevated language of honor and glory. Even as he acknowledges the seductive power of the idea of lost innocence, Larkin also suggests that it is complicated, even deceptive. Individuals like the anonymous children and husbands who populate his lines can easily be imagined as innocent. Imperial nation-states that have spent the last few centuries conquering most of the rest of the globe are another story.

Image Ernest Hemingway recuperating at an American Red Cross Hospital in Milan in 1918. Credit... Corbis

This was clear enough to Larkin, whose patriotism rested on the notion that England was the worst place on earth with the possible exception of everywhere else. The first time he uses the phrase “Never such innocence” he qualifies it with “never before or since,” suggesting that the particular Edenic aura that hangs over the prewar months of 1914 may be its own kind of illusion. To imply that Britain (or for that matter any other combatant nation) was somehow more innocent than ever on the eve of catastrophe is to register an aftereffect of the catastrophe itself.