The Second World War was the making of Evelyn Waugh, though he didn’t appreciate this at the time. Almost too old to fight – he was 36 when the war broke out – Waugh drifted in and out of various glamorous-sounding units (the Royal Marines, the commandos, the Royal Horse Guards) but never saw any serious action. His snobbery and cantankerousness made him a poor officer. Lord Lovat once said that he had chucked Waugh out of the commandos to save his life: as soon as Waugh led his men into battle, Lovat feared, they would seize the opportunity to shoot him.

From this disappointing material, however, Waugh crafted his masterpiece, the Sword of Honour trilogy. It was originally published, over a period of 13 years (1951 to 1964), in three separate volumes, so as to make him more money. Reviews were mixed: people preferred Brideshead Revisited. But it’s Sword of Honour – rambling, unwieldy, frustrating though it is – which does most to stake his claim as the 20th century’s greatest novelist.

When I first read it in my early 20s, I was disappointed that there was so little combat in it. Now that I’m older, I realise that this is part of its strength: it’s not really about war at all, but about something much bigger – about life itself and our quest for meaning in a world which makes so little sense.

It follows the attempted military exploits of the semi-autographical Guy Crouchback – middle aged, and Catholic, as the author was; richer and posher, as Waugh would like to have been. He sets out, full of high ideals, hoping to prove himself in battle like his knightly ancestors. But ahead lies only disillusion, with brief bouts of futile peril in Senegal, Crete and Yugoslavia, punctuating long periods of aching self-doubt, drudgery and boredom.

As heroes go, Crouchback is almost a cipher: sexless, phlegmatic, uncharismatic. 

But his essential dullness serves to ground in reality a series of events and characters so bizarre, colourful and outré they might have escaped from Waugh’s early satirical novels.

There’s Trimmer – aka McTavish – the handsome, proletarian hairdresser recast, purely for propaganda purposes, as a war hero after a confected raid on enemy territory whose only casualty is a dog; Crouchback’s brother officer Apthorpe, the ridiculous old Africa hand whose most treasured possession is the portable toilet he calls his “thunder box”; Brigadier Ritchie-Hook, the insanely brave, savagely bloodthirsty First World War veteran who returns from a lunatic beach raid on West Africa cradling a black man’s severed head; Guy’s ex – the appallingly fickle and flighty Virginia Troy – based, as all Waugh’s ghastliest females were, on his own first wife “She Evelyn” Gardner.

There’s also something quintessentially conservative in its pervasive religious theme, where personal acts of good behaviour are seen as the best route to redemption.

But because this is the work of a mature, bruised, increasingly religious novelist with an eye on posterity, not a flippant, brittle, bright young thing on a mission to shock, all this preposterousness serves a deeper moral purpose. It’s there to tell you that war – at least in Waugh’s view – is the bleakest of black comedies in which no good deed goes unpunished but where shits, incompetents, cowards, and even traitors too often prosper.

For its initial readership this would have been a brashly insensitive viewpoint. Even today, it comes across as quite outrageously cynical, bitter and perverse as a judgment on Britain’s finest hour. But while we may shudder at Waugh’s callousness – this, remember, is the father who refused to visit his own son as he lay in hospital in Cyprus shot almost to death in a machine gun accident – we may also find it hard not to admire his cool, observational detachment. If, as Graham Greene suggested, great writers need a “splinter of ice” in their hearts then Waugh had a whole iceberg’s worth.

We still haven’t quite established, though, what makes the book so good. In part, it’s the sublime technique. Elegant, economical, never a word out of place, ever adept with the mot juste, Waugh’s prose style is simply matchless. (As too is his dialogue, so authentic, honed, perfectly formed that he almost never needs to add adverbs to explain how it is spoken – or even needs to tell us who is speaking).

In part, it’s his sheer range: from broad comedy to sudden pathos; farce to tragedy; domesticity to Stuka attacks; fashionable London restaurants to dreary south coast training camps; laird’s dining halls to bombed-out Cretan villages; hallucinogenic sea voyages to grand Catholic funerals; literary pseuds, society hostesses, decent but stupid officers (poor “Fido” Hound), African witch-doctor abortionists, Jewish refugees… All human life is here, all drawn with an engagement and fluency and breadth of sympathy quite remarkable from such a crashing snob.

And even if it isn’t the 20th century’s greatest novel, it almost certainly qualifies as its greatest conservative novel. Besides the obvious reasons – the reverence for tradition and the suspicion of the novel – there’s Waugh’s relentless, unfashionable, clear-eyed contempt for the way his hero’s compatriots and allies keep deluding themselves as to the evils of Communism. The book’s title refers in part to a ceremonial sword forged by the British in honour of Stalin’s glorious victory at Stalingrad and exhibited at Westminster Abbey. Crouchback pointedly refuses to join the queues to see it, recognising that Stalin and Hitler are as bad as each other.

There’s also something quintessentially conservative in its pervasive religious theme, where personal acts of good behaviour are seen as the best route to redemption. We are told by the book’s moral touchstone – Guy’s devout and kindly father – that “sub specie aeternitatis” “quantitative judgments do not apply”. He means that it’s the quality of your deeds, however small, that counts in the eyes of God.

When I first read it in my early 20s, I was disappointed that there was so little combat in it. Now that I’m older, I realise that this is part of its strength: it’s not really about war at all, but about something much bigger – about life itself and our quest for meaning in a world which makes so little sense. I cannot recommend reading – or re-reading – it highly enough.