IN 1941 Franz Rademacher, who handled Jewish matters for Germany’s foreign ministry, took a business trip to Belgrade. His expense claim disclosed the purpose of his visit: “liquidation of Jews”. This chilling detail appears in “Das Amt und die Vergangenheit” (“The Ministry and the Past”), an 880-page history of the ministry during and after the Nazi era, commissioned by the ministry itself. It shows, says Eckart Conze, one of the four authors, that the ministry “co-operated…with Nazi crimes, including the murder of Jews.” It was “a criminal organisation,” he told Der Spiegel, a magazine.

Earlier studies have made this point. Still, the image lingered, inside and outside the ministry, that Hitler’s diplomats were a cut above other servants of his vile regime. They came from Germany’s upper crust, not the downmarket fanatics that supported the Nazis. They were seen as reluctant accomplices, often acting as “sand in the machine” of a murderous dictatorship, as one diplomat puts it.

“Das Amt” will shatter that idea. It shows the diplomats to have been inventive and energetic agents of Nazism. Upset that Jewish émigrés in southern Manchuria were being taken for Germans, the consul there proposed stamping the covers of their passports with a red J, a suggestion that Heinrich Himmler, the Gestapo chief, took up. The historians unearthed a letter written in 1936 by Ernst von Weizsäcker, later among a half-dozen diplomats convicted of war crimes at Nuremberg, that called for stripping the novelist Thomas Mann of his citizenship. Diplomats arranged for the deportation of Jews from countries ruled by the Nazis or by allied regimes.

After the war Hitler’s diplomats regrouped to serve a democratic government willing to overlook their pasts. They protected each other. In the 1950s and 1960s the ministry’s legal team helped Germans wanted for war crimes to avoid arrest in neighbouring countries. Even Willy Brandt, a Nazi-resister who became the first Social Democratic foreign minister and is a hero to his party, worked with a diplomat who had helped deport Jews from France.

“Das Amt” came about because Joschka Fischer, the first foreign minister from the Green party, could not abide the whitewashing. In 2003 he banned an employee newsletter from publishing eulogising obituaries of former Nazis. Two years later 128 former diplomats rebelled by honouring a deceased colleague with a showy newspaper notice. Mr Fischer’s response was to summon the historians’ commission. The results, he says, are “deeply depressing.”

“Das Amt” continues a “widening of the sphere of complicity” that marks Germany’s drawn-out reckoning with its past, says David Art, a political scientist at Tufts University in Massachusetts. In recent years public exhibitions have looked at the roles of the justice ministry and the Wehrmacht under the Nazis. A new exhibition in Berlin examines ordinary Germans’ veneration of Hitler. At the aristocratic Auswärtiges Amt the soul-searching has just begun.