Good-bye to All That by Robert Graves (Anchor, $16). Graves’ brilliantly observed World War I memoir is a useful reminder that in the history of warfare, there have always been others worse off than you. Other combat books are more violently shocking, but Graves’ has the most sober humanity.

Catch-22 by Joseph Heller (Simon & Schuster, $16). I loved Heller’s masterpiece before I joined the British army, but didn’t realize how scarily accurate it was. War shouldn’t be laugh-out-loud funny, but it can be, and Heller’s book catches that expertly. Despite its dark humor, Catch-22 retains a glimmer of hope—“Yossarian lives.”

The Oxford Book of English Verse (Oxford, $45). Something about the pace of soldiering—boredom and drawn-out pressure giving way to frenzied bursts of adrenalin—lends itself to poetry. The quiet before the patrol, the long homesick night, the exhausted but exalted feeling of survival before collapsing asleep in the dirt: The grandfather of anthologies has something for all occasions.

Tristram Shandy by Laurence Sterne (Wordsworth, $5). There is something so gentle and human about Sterne’s inspired novel, and I liked to keep it close by as a counterpoint to the violence of conflict. A million miles in every sense from Baghdad or Helmand, but, in its own way, a great anti-war book. It’s also one of the funniest and cleverest books in the English language.

Flashman by George MacDonald Fraser (Everyman’s, $30). Fraser’s scoundrel hero is beloved by every soldier who deep down likes to be reminded that someone somewhere is getting away with it and having a good time. Fraser’s invented “Flashman Papers” are so riotously entertaining that one almost doesn’t notice his effortless style.

The U.S. Army / Marine Corps Counterinsurgency Field Manual (Univ. of Chicago, $15). When they say that Gen. David Petraeus “wrote the book” on counterinsurgency, they aren’t just spouting a cliché. First issued at the end of 2006, this book is required reading for anyone engaged in our current wars and should be for anyone seeking to understand them.

Patrick Hennessey is a former British army captain and the author of The Junior Officers’ Reading Club, an acclaimed memoir now available in the U.S.