THE YOUNG soldiers of Hitler's Sixth Army marching across the Don steppe towards the Volga city of Stalingrad in the summer of 1942 had tanned brows and sunglasses to reduce the glare from fields of sunflowers and wheat stretching over the horizon. Collective farms torched by the Soviets gradually gave way to cherry orchards and tidy Cossack hamlets, where the inhabitants gave the invaders so much food that they were sometimes sick on a surfeit of ham and honey. In late January, 1943, the remnants of the same army, by now bearded, emaciated, lice-ridden, and with dulled eyes averted, crawled out of their pulverised dug-outs. Off they tramped in vast columns of what looked like Dickensian vagrants into a captivity that meant death for many, or release in the mid-1950s for those who survived slave labour in Soviet gulags.

This contrast is the principal theme of Antony Beevor's humane and thoroughly researched account of the battle of Stalingrad, a book which definitively reminds us that modern warfare is inconceivably terrible. In line with much recent scholarship on the Eastern Front, he emphasises both the suffering of ordinary soldiers and, in the case of Sixth Army, their complicity in atrocities against Russian and Jewish civilians along their line of march from the Ukraine to the banks of the Volga. Beevor is also alert to those caught on the wrong side of the conflict, whether Russian prisoners pressed into German service as an alternative to starvation in miserable conditions, returning Soviet POWs who went straight to the gulags as a form of ideological decontamination, or captured German officers who found themselves spouting Communist propaganda in the so-called National Committee for Free Germany.

Stalingrad was a by-product of Hitler's "Operation Blue": the relaunching of the 1941 "Barbarossa" invasion, stalled before Moscow that winter. The summer offensive involved a lunge towards the oilfields of the Caucasus, while the Sixth Army and its Axis allies neutralised the arms factories of Stalingrad and cut traffic on the Volga from the south up to Moscow. Partly because of the symbolic significance of the city (renamed because of Stalin's alleged role in its defence during the Civil War), both totalitarian dictators construed its conquest as a contest of wills played out with the lives of hundreds of thousands of soldiers and civilians, for Stalin refused to evacuate its inhabitants, while Hitler would not countenance withdrawal when the rate of attrition became murderous.

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Paradoxically, the Luftwaffe's opening bombing campaign - which killed 40,000 people - created a terrain of collapsed walls, jagged concrete, and twisted metal favouring the Soviets. The latter's high desertion rate was swiftly checked by officers who thought nothing of lining up their men and shooting every tenth soldier until their magazines were empty. Whereas the German army excelled at encircling movements, hoovering up hundreds of thousands of prisoners, the Soviets were adept at close-quarter combat with knives and bayonets during the night and, above all, at sniper warfare. Star snipers, such as the former shepherd Zaitsev, notched up 149 kills, using ingenious ruses to make the Germans offer them a clean target for the split second it took to blow a man's head off. Supported from the east bank of the Volga, the Soviets trapped in the elongated, riverine city fought as close to the Germans as possible to minimise the effectiveness of their artillery or airpower. Major buildings changed hands as often as 15 times in five days with occupancy of each floor resembling a layer-cake of brown, grey, or green uniforms, all endeavouring to kill each other. A once highly- mobile German force regressed into "storm battalions" or assault troops more typical of the trench warfare of an earlier conflict.

While Hitler urged his forces into this killing ground, in September Stalin authorised Marshal Zhukov's "Operation Uranus", a vast pincer movement encircling German and Axis troops at a depth which made a break-out or relief inexpedient. Inside Stalingrad, the remarkable General Vasily Chuikov clung on for a further 45 days, while unknown to him, about a million Soviet troops and vast numbers of guns, tanks and aircraft moved into position. Much had changed since the previous year when demoralised and drunken Soviet soldiers had been prevented from fleeing by secret police units fully prepared to kill them, or draconian edicts which denied rations to the families of those evincing defeatism. A rabble drunk on vodka or anti-freeze was becoming an army.

Unlike Hitler, Stalin was prepared to be advised by his military commanders, rather than imagining that his worm's eye experience of warfare qualified him to direct entire armies. Whereas Hitler was loath to conscript German housewives into factories, Stalin had entire plants and their workforces moved thousands of miles, where they churned out basic, but effective, weapons such as the T-34 tank. Communist egalitarian claptrap was replaced by the verities of orthodoxy, Russian nationalism, elitism and hierarchy, as gold braid and guards divisions were reintroduced, and interfering political commissars were sidelined. By contrast, the Axis forces began to fracture, as Hungarians and Romanians resented the haughty Germans, and Austrians and Bavarians fell out with the "Prussians". At the apex it was an uneven contest between Soviet generals whose experience ranged from the Spanish Civil War to Manchuria, and a German commander, Friedrich Paulus, who had never commanded a large formation, and who was often prostrated with dysentery. He lacked both grit and grandeur.

About a quarter of a million German and Axis troops were duly trapped inside the Stalingrad cauldron. Hitler's decision to leave them there while he imagined non-existent SS tank divisions hurtling to their relief, was influenced by Goering's airy assurance that the Luftwaffe could drop 500 tons of supplies per day, a figure which ignored Soviet anti-aircraft guns, fighters, or atrocious weather. In fact, nothing approaching these quantities was flown into Stalingrad, whose attackers-turned-defenders ran out of ammunition, food and fuel. The scenes accompanying the return flights were heartbreaking, as ruthless medical triage left stretcher cases beside the runways, while the ambulant wounded had to be prevented from rushing the planes by armed military policemen. The engines of overloaded transport planes screamed before falling backwards out of the sky, in surely the most depressing spectacle for those still fighting below.

Beevor uses army medical evidence to moving effect to describe the sicknesses to which most soldiers succumbed and their letters home to suggest their deteriorating psychological condition. Colonies of lice the size of grapes lived in beards and eyebrows, or had to be scraped off clothing; mice ate frost-bitten toes. The frozen ground meant that enemy mortars and shells bounced back into the air resulting in terrible stomach and head wounds. There were no analgesics in the airless subterranean field hospitals and sharpened tin lids stood in for scalpels. Prisoners of war suffered absolute neglect with all but 20 of 3,500 Russians starving to death after vainly trying to eat each other. Christmas and New Year 1,500 miles from home engendered many plangent reflections, while the Soviets conducted an aural assault consisting of sinister tango music and injunctions to surrender, pre-recorded by exiled German Communists.

Despite Hitler's talk of fighting to the penultimate bullet, and Goering's invocations of the Spartans at Thermopylae, the newly promoted Field Marshal Paulus surrendered on 31 January, 1943, bringing German guns to an eerie silence, while Russia's NKVD murdered the huge number of Russian auxiliaries found to be fighting on the German side, and finished off German or Axis wounded where they lay. Ninety-thousand German prisoners set off on the long march to Soviet gulags from which the majority never returned. About half a million Russians and 147,000 German and Axis troops lay dead within the ruined city or frozen rigid on the windswept steppe.

Stalingrad may have merely winded Hitler's legions - for the preceding defence of Moscow and the subsequent battle of Kursk were surely as significant - but it deserves its grim reputation. The battle checked an unbroken series of German victories, beginning with Poland and the fall of France, and the impetus of the relaunched Russian campaign. It boosted the morale of the Red Army, whose generals now had at their disposal a formidable force, capable of executing complex combined operations. It also erased memories of the purges and the obloquy of the 1939-41 Nazi-Soviet Pact, thus relegitimising European Communist parties, and became one of the key elements in the Soviet sacralisation of the "Great Patriotic War", indirectly ensuring a 40 years' lease of life the surviving form of totalitarianism, which had spread with the Red Army across eastern Europe.

! Michael Burleigh is Distinguished Research Professor in Modern European History at Cardiff University