The first meeting between Walter Ben­jamin and Bertolt Brecht did not go well. It took place in Berlin in November 1924 at the home of Asja Lacis, a Latvian actress and theatre director. She recalled in her memoirs, “The conversation never got going, and the acquaintanceship petered out. I was confused. Was it possible that Brecht, such an intelligent person, could find nothing in common with Walter, a person of such intellectual curiosity and wide interests?”

Benjamin, then 32 years old and unable to secure a university lectureship, was emerging as one of Germany’s pre-eminent cultural critics. His writings covered subjects as varied as art, children’s literature, food, film, gambling, graphology, Marxism, photography and toys. He wrote essays on the concept of history, the social impact of mass media, and 19th-century Paris. He produced radio programmes and translated texts by Baudelaire and Proust. There was no guiding philosophy. Yet the influence of certain traditions (such as German idealism, Rom­anticism and Jewish mysticism) was clear.

Brecht was six years younger than Benjamin. By the time they met, he had established himself as a gifted poet and playwright whose first works, such as Baal (premiered in 1923), combined lyrical force and moral dissent, especially on the theme of sexuality. Brecht’s plays departed from the aesthetic conventions of melodrama and developed a style called “epic theatre”; he argued that spectators should not be able to identify emotionally with the characters before them but should take a critical view of the action on stage instead.

This was not just a visual strategy. It was driven by Brecht’s commitment to Marxism. If audiences identified with the emotional agonies of heroes such as Hamlet or Lear, then the Marxist notion that human nature is not fixed but a product of shifting historical conditions would be undermined.

The friendship between Benjamin and Brecht finally bloomed in May 1929. What brought them together, as Erdmut ­Wizisla writes in this affectionate book, was not only a slow convergence of aesthetic and political interests, or their collaboration on projects such as the aborted journal Krise und Kritik. It was, above all, the experience of exile that cemented their mutual affections. By 1933, with the rise of national socialism, thousands of intellectuals and writers had fled Germany. Strewn across Europe, they were the human flotsam of a culture that had been wrecked in the name of Teutonic order and purification.

Brecht admitted that it was “precisely the vileness and fearsome character” of Nazism and “the mediocrity of its personnel that prevented many of us from taking the measure of this evil in all its profundity and shattering significance”. He left for Denmark in February 1933. Benjamin had gone to Ibiza a year earlier, after which he spent some time in Nice and Paris. He then joined Brecht at the house on Skovsbostrand for extended periods in the summers of 1934, 1936 and 1938. There the two of them worked on the garden, listened to the radio, read the papers and wrote and commented on each other’s work. They took trips in to town in Svendborg and, most importantly, they played chess. It is no coincidence that three out of the four existing photographs of Benjamin together with Brecht show them playing chess. The game provided some friendly competition and exposed their contrasting personalities: the mercurial self-confidence of Brecht against the quiet, ironclad focus of Benjamin (Brecht usually won).

As the director of the Brecht and Benjamin archives in Berlin, Wizisla is the best-placed person to collate the reams of letters, diary entries, manuscripts, minutes and marginalia to tell this story. Now and then, the book reads like an archival inventory, and Wizisla’s singular learning might prove frustrating for readers with no prior knowledge of Benjamin’s or Brecht’s writings. What the book does do, however, is show how they had a critical bearing on each other’s work. For example, Brecht’s Days of the Commune (1948-49), a play about the rise and fall of the Paris Commune in 1871, contains evidence of his discussions with Benjamin on Baron Haussmann’s renovation of Paris in the 1850s, while the latter’s Arcades Project, an unfinished, rough-hewn meditation on the relationship between writer and metropolis, bore the imprint of Brecht’s “Ten Poems from a Reader for Those Who Live in Cities” (1926-27). Wizisla is more interested in the genesis and evolution of intellectual projects – the calculations in the margins – than he is in their final answers.

The prevailing assumption is that Brecht took advantage of Benjamin’s unqualified affections, or that he somehow corrupted his thinking. Benjamin’s friends were wary of Brecht. Gretel Karplus expressed “great reservations”, as did Theodor Adorno, who lamented: “Under Brecht’s influence, Benjamin is doing only stupid things.” The French historian Marc Bloch described the “harmony between the Alexandrian genius of Benjamin and the unwashed genius of Brecht” as “curious beyond measure”, while the journalist Günther Anders, who at one point was married to Hannah Arendt, noted the great differences “in style and social background”. The philosopher and historian Gershom Scholem, a friend of Benjamin’s since 1915, accused Brecht of diverting Benjamin away from the Judaic tradition and towards Marxism.

Wizisla’s book is a welcome corrective to this fancy. It is obvious that Brecht’s poetry captivated Benjamin. It was Benjamin who first asked to meet Brecht, and who tirelessly hyped Brecht’s work, pitching it to journals as a literary agent might. Wizisla notes that unlike in Benjamin’s “ordinary” style – that is to say, his own texts were composed without the invention of plot, or poetic devices such as meter or rhyme scheme – Benjamin “saw something original in the link between political intention and creative presentation to which Brecht aspired”.

But Brecht encountered in Benjamin, as Arendt described him, “the most important critic of the time”: someone who supported his efforts and recognised his originality within the exiles’ broken republic of letters. Benjamin was the first to encourage Brecht to amplify the political, anti-fascist core of his poetry. He was also a valued reader of the manuscripts that Brecht made available to him and a touchstone of knowledge and opinion who proved vital to his development as a poet and playwright.

Wizisla describes a friendship based on “conspiratorial rapport” – exclusive jokes, shared secrets, joint ambitions. Such harmony glows brighter set against the entropy of 1930s Europe. Wizisla excels at connecting Benjamin’s and Brecht’s “symptomatic loss of faith in progress” to the development of certain aesthetic modes. The use of interruption, quotation, shock, experimentation and montage reflected the increasingly disordered nature of European politics.

In September 1940 Benjamin planned an escape to the US via Portugal, as it became apparent that life in Nazi-occupied Europe would be unbearable. When officials at the border refused him and his companions the right to transit through Spain, he took his own life in a small village in the Pyrenees. He was poor – freelance writing didn’t pay well – and prone to depression, and he had contemplated suicide in the past. With the establishment of the Third Reich in 1933, he was damned to eternal wandering, no longer a migrant but a refugee. He became one of those exiles whom Goebbels described as “corpses-in-waiting”.

An inscription on the memorial outside the cemetery where he was buried, taken from his essay “On the Concept of History”, reads: “It is more arduous to honour the memory of the nameless than that of the renowned.” The memorial sits atop a small bay overlooking the Mediterranean, where today’s migrants and refugees from the Middle East die the same cruel and anonymous deaths. News of Benjamin’s suicide didn’t reach Brecht until the summer of 1941:

I’m told you raised your hand

against yourself

Anticipating the butcher.

After eight years in exile, observing

the rise of the enemy

Then at last, brought up against an impassable frontier

You passed, they say, a passable one.

Empires collapse. Gang leaders

Are strutting about like statesmen.

The peoples

Can no longer be seen under all

those armaments.

So the future lies in darkness and

the forces of right

Are weak. All this was plain to you

When you destroyed a torturable body.

Poetic tribute was the only way that Bertolt Brecht knew how to honour his absent friend, who had once sat “at the chess table in the pear tree’s shade”, as the world collapsed around them.

Benjamin and Brecht: the Story of a Friendship by Erdmut Wizisla. Translated by Christine Shuttleworth is published by Verso (272pp, £16.99)