Hitler’s principal object in sending his legions into Italy in 1943 was to stem an Allied advance aimed at penetrating Germany’s southern frontiers and launching air strikes on the precious Balkan oil fields. The incursion presented an ideal opportunity, however, for the Führer and others, the insatiably acquisitive Hermann Göring foremost among them, to snap up the masterworks of Italian art for their personal collections or to enrich the great public galleries of Germany. Local feeling in cities such as Rome, Florence and Milan no longer counted. Italy’s perfidy in surrendering to the Allies was to be answered with a thoroughgoing process of humiliation, which included some astute cherry-picking from museum walls and church altars for the sake of the Reich’s aesthetic edification.

Nothing on this scale had taken place in Italy since Napoleon’s commissars had crated up Raphael’s Madonnas in Rome and the bronze horses of St Mark in Venice for dispatch to Paris. As Robert M Edsel’s vivid, keenly researched and sometimes heart-rending narrative reminds us, the spoliation had already begun under Mussolini. Hitler demanded, and was given, the contents of the great German art-historical and archaeological libraries in Florence and Rome, while the Duce, bored by art, sanctioned the export of many paintings and sculptures (including 34 cases for Göring in 1941 and 67 the following year) in the teeth of laws forbidding the removal of the national patrimony.

After 1943 it was open season for Nazi looters, renewing a tradition stretching back 1,500 years to the days of the Goths and the Lombards. Though the German high command instituted the Kunstschutz, an official art protection policy, its operation was distinctly patchy, depending on the conscientiousness of individual officers in restraining their men from wanton depredation and vandalism. While Allied bombing raids flattened buildings such as the Camposanto, Pisa’s medieval burial cloister, and Padua’s Eremitani church with its Mantegna frescoes, sheer spite against the Italians motivated the German troops in Naples who wrecked the university, destroyed the entire contents of the Museo Filangieri and made a bonfire of the civic archives.

Swift action was needed by American and British armies pushing north to Rome and Florence if anything worthwhile was to be preserved amid the pillage and devastation. The Military Government School, set up at Tizi Ouzou in Algeria, trained specialist officers in salvage and protection of monuments before dispatching them to face the challenges of rescuing Italian art from the impact of one of the Second World War’s longest and most bitterly fought campaigns. Edsel’s book concentrates chiefly on the experiences of two markedly different American officers, painter and teacher Deane Keller and art historian Fred Hartt. The former comes over as a regular guy, proud to be in uniform but wary of authority and inherently modest as to his role and influence. ‘The way I help is to talk with people, serve as interpreter – give help to any of the others who need it, and once in a while interject something in a meeting.’ Hartt, on the other hand, a repressed homosexual with a passion for French cathedrals and Oriental screens, courted publicity for his role as Italy’s artistic saviour, earning resentment from Keller, who mocked him as the ‘Tuscany kid’ but could hardly have done without his professional expertise.

The story of the two men’s uneasy collaboration, among the shattered frescoes, dismembered statuary and corridors stacked with the choicest spoils of Florentine galleries, is cleverly interwoven with the vicissitudes of several thousand artworks shunted by the Germans on open trucks along bomb-cratered roads as the battle front edged northwards with agonising slowness. Edsel, with his unfailing narrative command, clearly relishes moments such as Hartt’s discovery, in a Tyrolean castle guarded simultaneously by Germans, American GIs and Italian partisans, of the Uffizi’s most prized canvases: a Botticelli here, a Signorelli there, a Caravaggio round the corner, with Michelangelo and Donatello sculptures in the coach house across the courtyard. Keller, instrumental in salvaging both the burnt-out Pisan Camposanto and Leonardo’s Last Supper from a ruined Milanese monastery, becomes a hero malgré lui, posthumously honoured by Pisa for his rescue of ‘a patrimony belonging to everyone’, with the interment of his ashes in the Camposanto’s sacred soil.

Edsel is judicious and even-handed in his assessment of the Nazi record in relation to Italian art treasures and his estimation of the enduringly controversial Karl Wolff, the SS general who negotiated the German surrender with future CIA chief Allen Dulles. He is at pains to emphasise the problems of the Kunstschutz officers in dealing with the rapacity of Göring’s myrmidons. Noting the essentially cosmetic nature of Wolff’s postwar prison sentence – he was given four years but freed almost at once through Dulles’s influence – Edsel sees his belated impulse towards delaying yet another consignment of paintings to Germany as an insurance measure in the run-up to ending hostilities.

Some arresting illustrations include a glimpse of the swastika flowerbed with which Fascist Florence welcomed Hitler; the Sitwell villa at Montegufoni piled full of Cimabues and Ghirlandaios; and the extraordinary brick silos built in the basement of the Accademia to protect Michelangelo’s Slaves and David from bomb damage. This book and Edsel’s earlier study The Monuments Men tell the story of the American contribution to saving Italian art for humanity. There is, as he periodically indicates, a British dimension to these heroic exploits still waiting to be unfolded. George Clooney, meanwhile, is turning the whole episode into a film. Will the Brits – including such distinguished figures as Leonard Woolley, John Bryan Ward-Perkins and Edward Croft-Murray – appear in walk-on roles as routine Holly-wood lip-curling Limey toffs? You have been warned.