The leader of the left, adored for his “authenticity” and destined for cult status, saw himself as a fighter for radical change. His transformed party was the biggest of its kind in Europe, and bursting with youthful vigour.

On the other side of the political spectrum lay the far right and its sinisterly absurd demagogues, thugs and ideological lunacies. Naturally, the leader of the left regarded these people with contempt and viewed his party as the only authentic resistance to them. For strategic reasons, however, he was willing to help them achieve a key part of their dream, which he shared. The dream was to break the loathsome old liberal order. Such a break, reasoned the leader, would create conditions under which the left would sweep to power and transform the country for the better.

Any similarities to Jeremy Corbyn and the Labour Party are far from coincidental. But the leader in question is Ernst Thälmann, chief of the German Communist Party (KPD) in the final years of the Weimar Republic. Thälmann is a tragic and disastrous figure. Dogmatic, passionate, stubborn and stupid, the former Hamburg dockworker divided the left and became one of the right’s first victims. Within weeks of Hitler’s takeover in 1933, he, along with thousands of other communists, was arrested and tortured. Unlike many of them, he survived in prison for 11 years before being murdered on Hitler’s orders in 1944.

After the war, the leaders of Communist East Germany built a personality cult around Thälmann, erecting statues and naming streets, a Berlin park and a metro station after him. The cult depicted him as the bravest and noblest of working-class heroes, Germany’s supreme anti-fascist martyr. That he had also been one of the Nazi regime’s unwitting enablers was erased.

History never repeats itself exactly, and there are obvious and big differences between conditions and politics in Britain now and those of Germany in the run-up to the Nazi dictatorship. But there are a few uncomfortable parallels.

For one thing, even our relatively mild versions of far left and far right seek momentous change – in this case a destructive Brexit – for ideological reasons. For another, the far left’s current mindset is reminiscent of one that had unintended consequences – and is doing so again.

In the 1930s, fear of Bolshevism persuaded many middle-class Germans to support Hitler (and led the Catholic Church to throw in its lot with fascism in Italy, Spain and elsewhere). These days, fear of Corbyn buttresses the worst Tory government in living memory. Worse, although we again face danger from the far right, the far left refuses to work with potential allies in the centre and centre left. Again. Instead, it spends much of its energy attacking them. The obsessive hatred for “Blairites”, “red Tories” and “centrists” is reminiscent of the KPD’s hatred of “social fascists” during the years when Nazism could have been stopped. If the phrase is new to you, you’d be forgiven for thinking it signified some form of fascism. It didn’t. “Social fascism” was the communist term for social democrats – and it helped pave the way to catastrophe.

In the words of Theodore Draper, the American former communist fellow traveller who turned against the party and became a historian, “the so-called theory of social fascism and the practice based on it constituted one of the chief factors contributing to the victory of German fascism in January 1933”.

The theory, developed in the early 1920s, favoured by Stalin and established as Communist orthodoxy by 1928, held that reformist social democracy was the worst enemy of the proletariat – worse than fascism – because it created false consciousness and made revolution, the party’s overriding goal, less likely. This notion derived from the left’s misunderstanding of the dark forces about to overwhelm it.

Thälmann and the KPD regarded fascists and Nazis as products and tools of capitalism. Since social democrats were also capitalists, it followed that social democracy, fascism and Nazism were simply different facets of the same oppression. To further the dream of a Soviet Germany, the party was willing to help the Nazis destroy democracy, thinking it could beat the Nazis easily in the aftermath.

Unlike the modern Labour left, the KPD’s antipathy to their centre-left rivals derived in part from memories of a recent crime against them. In January 1919, after Germany’s defeat in the First World War and the fall of the Kaiser, the new Social Democratic Party (SPD) government led by Friedrich Ebert used the far-right Freikorps militias to help suppress the Spartacist uprising, led by KPD founders Rosa Luxemburg and Karl Liebknecht. In the process, Freikorps men tortured and murdered Luxemburg and Liebknecht.

In the first part of his Hitler biography, Hitler, 1889-1936: Hubris, Ian Kershaw describes these killings as “the symbolic sealing of the rift within the working-class movement that throughout the Weimar Republic prevented any united front being formed against the growing threat of National Socialism”. By the late 1920s, though, the KPD had largely purged itself of Spartacists and become a Stalinist party. Thälmann took his instructions from Stalin and his hatred of the SPD was essentially ideological.

With hindsight, his relaxed attitude to the threat of Hitler seems astonishingly foolish. For example, as Russel Lemmons shows in his 2013 book about Thälmann, Hitler’s Rival, when the Nazis made their electoral breakthrough in the Reichstag elections of 1930 (winning 18 per cent of the vote to become the second-largest party) Thälmann insisted that if Hitler came to power he was sure to fail and this would drive Nazi voters into the arms of the KPD.

Foreshadowing the 2017 claim that Labour actually won the general election it lost, the KPD newspaper the Red Flag even hailed the KPD’s defeat in that election (up by 2.5 per cent to 13.1 per cent) as a victory on the grounds that communist voters were ardent revolutionaries (“one communist vote has more weight than ten to 20 national socialist votes combined”). The 1930 election left the Social Democrats and KPD with almost 40 per cent of the seats in the Reichstag between them. In November 1931 the SPD suggested the two parties work together but Thälmann rejected the offer and the Red Flag called for an “intensification of the fight against Social Democracy”.

Along the way Thälmann made any number of tactical blunders. In 1925, for example, against the advice of Bolshevik leader Grigory Zinoviev, the KPD leadership refused to stand Thälmann down in the second round of the German presidential election. This split took enough votes away from centre candidate Wilhelm Marx to give the First World War general Paul von Hindenburg a narrow victory. In 1933, Hindenburg appointed Hitler as chancellor, then signed the decrees enabling the Nazi terror against the left after the Reichstag fire.

As the Nazi menace intensified in the early 1930s, Thälmann continued to be sanguine. As late as February 1932, he was arguing that “Hitler must come to power first, then the requirements for a revolutionary crisis [will] arrive more quickly”. In November 1932, just three months before Hitler’s takeover, the KPD and Nazis even worked together in the Berlin transport workers’ strike.

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Is it fair to speak of this in the same breath as Corbyn’s de facto alliance with the right on Brexit? The stakes are less high, and the specifics are so different it’s hard to compare.

Corbyn’s lack of enthusiastic campaigning may have hampered Remain in the referendum. He has made a damaging Brexit more likely by failing to oppose it, and by whipping his MPs to abstain or vote with the government at key moments since 2016. But this isn’t the same as seeking a Soviet Britain, or enabling Hitler. Corbyn isn’t trying to end democracy, or co-operating with Nazis, or taking orders from Stalin. He hasn’t even created a party paramilitary wing.

The Labour left’s assault on the liberal centre is driven by a quite different political agenda to that of the KPD. But it runs a similar risk of hollowing out the political constituency best capable of resisting the radicalism of the right.

History teaches us that it is dangerous and naive to expect only the radical left to benefit politically from the kind of economic chaos and social upheaval a hard or no-deal Brexit would bring.

Thälmann was at least open about his objectives. Corbyn rarely explains his strategy, and even talks blithely about a “jobs-first Brexit” while backing a course liable to wreck the regions, damage the NHS and blight the future of the young.

Thälmann’s approach was also contradictory and ambivalent. On one hand, his Communist militias fought bloody and often lethal turf battles with Nazi stormtroopers and police. On the other, he refused to provide effective political opposition to the Nazis. There were some half-hearted attempts to work with SPD rank and file, but Thälmann never stopped regarding the SPD leadership as anathema and refused to co-operate with them in any significant way until it was far too late.

Only in February 1933, by which time the battle was already lost, did Thälmann finally grasp the situation and propose a united front with the SPD and the free and Christian trade unions – under his own leadership, of course – to prepare for a general strike to bring down the new regime.

When the Nazis started rounding up leftists, Thälmann escaped but his hiding place on the Kaiserallee (now Bundesallee) in Berlin was revealed by a tortured comrade and Thälmann was arrested on 3 March and taken to prison. In 1939, Stalin could easily have had Thälmann released as a condition of the Nazi-Soviet Pact, but he didn’t say a word. In August 1944 Hitler ordered Thälmann “liquidated”. SS officers drove him to Buchenwald, shot him in the courtyard of the camp crematorium and burned his body immediately.

Lemmons argues that Thälmann “went to his grave believing that the SPD represented the forces of ‘social fascism’ and was no better than Hitler’s party”. That, and his subservience to Stalin, meant Thälmann “failed his people in its greatest hour of need”. The KPD did “nothing to stop the Nazi seizure of power – indeed they had welcomed it as what they considered to be the dying breath of German imperialism”.

Even if the worst Brexit predictions come true Jeremy Corbyn is unlikely to suffer so terrible a fate. But if a disastrous Brexit does occur, the verdict of history is unlikely to be much kinder.