International Booker winner David Diop: ‘It’s war that’s savage, not the soldiers’

David Diop, the first French novelist and the first writer of African heritage to win the International Booker prize, along with his translator Anna Moschovakis, likes to seek out stories in historical gaps and missing narratives. He was struck by emotion when reading the letters of young French men fighting in the trenches of the first world war – shellshocked teenagers faced with the unmeasurable carnage of trench warfare, a sacrificed generation who often died before their letters reached home.

The novelist, who was born in France but spent his childhood in Dakar, Senegal, after his French mother and Senegalese father met at university in Paris in the 1960s, was floored by the young soldiers’ “intimacy with war”. His novel, At Night All Blood Is Black, is a gripping, twisty account of industrial warfare, colonialism, violence, youth and friendship. It was a massive critical hit and bestseller in France, winning several prizes across Europe. After more than 100 years of first world war literature, in all forms and all languages, critics found something new in Diop’s modern take. It was “hypnotically compelling”, the Booker judges said.

“Because I have a double cultural sensitivity,” Diop says, “I wanted to find out if there were any letters written by the tirailleurs sénégalais [the west African riflemen from French colonies brought over to fight in the trenches]. And my research wasn’t conclusive. There are letters, of course, but they are impersonal, administrative letters. You have to remember that letters were monitored to keep up the morale of the troops and the country. It’s also possible there was a form of self-censorship among the African riflemen.”

France, which had a vast colonial empire at the time of the first world war, deployed more than 135,000 African riflemen on European battlefields, where at least 30,000 were killed. Despite being referred to as Senegalese, they came from all over west Africa, including Senegal, Mali, Niger and Burkina Faso, and never got the prominence they deserved in French history books. The injustices of the poor pay and low veterans’ pensions of African fighters deployed by France in both world wars were well documented, but the inner lives of soldiers brought from France’s African colonies to the trenches – their lived experience of the European war – had not really been told.

Diop first considered filling the gap by writing his own fictional soldier’s letter. But he found more “emotional intensity” in the stream of consciousness of a young rifleman in the trenches. His novel tells the story of two childhood friends deployed from Senegal (the original French title, Frère d’âme – literally, soul brother – is a play on the term frère d’armes, or brother in arms). When one, Mademba Diop, is killed in the trenches, the other, Alfa Ndiaye, descends into his own way of coping – diligently committing the extreme violence expected of him by the war and carefully slicing trophy hands from corpses. From here, the novel twists and turns in shocking and surprising ways to the end, taking in the story of the protagonist’s Senegalese family.

Diop says he didn’t want to write a historical novel. He deliberately does not specify exact battlefields, battalions, dates or places. “I wanted to show that this character – like a lot of soldiers – didn’t know where they were on the front.” What mattered to Diop was fiction’s ability to convey raw emotion. “I think fiction can move you emotionally, then it’s for history to explain things,” he says.

Diop is known in France as a master of unpicking the mechanics of prejudice. His first novel, published in 2012, about a delegation from Senegal coming to Paris’s Exposition Universelle in 1889, was inspired by historical accounts of 19th-century “human zoos” and European “spectacles” of black people. He is a lecturer in 18th-century literature, whose current research, at the University of Pau in south-west France, focuses on 18th-century representations of Africa, particularly accounts and images by travellers. His forthcoming novel, due out in France in August, tells the story of a European traveller in Africa. “What interests me are the sources of information that feed representations of the other, the African other, or the Asian other,” he says.

In the first world war, west African riflemen were caught in the crossfire of dehumanising French and German propaganda. For the purpose of war, they were shown as bloodthirsty savages. Then, to shore up European populations’ view of empire, they were shown as naive infants.

“The French army played on the idea that Senegalese riflemen could inspire fear in the Germans,” Diop says. “France provided a machete as part of African troops’ uniform – they were the only soldiers to be given that particular weapon. That shows the intent to scare the enemy with the image of a savage black soldier. On the other side, I saw caricatures in a 1916 Berlin paper of an African rifleman with skulls hanging from a belt round his waist, a savage rictus grin, and a sort of joy in his eyes that he was going to kill the enemy.”

Diop adds: “Prejudices were attached to the Senegalese riflemen for strategy and combat reasons. But also in France the African soldier was presented as saviour of the motherland, and a giant child whose image was used to advertise the chocolate drink Banania … We have the savage, bloodthirsty black for the enemy, and for the French it’s a brave soldier who has a certain naivety.”

All this is woven deep into Diop’s language, which is the novel’s great stylistic triumph, cited by judges in all the book’s prize nominations (of which there were 10 in France alone). Although Diop wrote the stream of consciousness in French, the rhythm of the language reveals that the main character, Ndiaye, thinks in Wolof. It was a way for Diop to amplify the internal voice of a young man who, like so many other African troops in the French colonial period, had no way of making himself heard. The complexities of this rich inner monologue expose the absurdity of the deliberately rudimentary French that was taught to colonial troops so they could take orders in the trenches.

Diop read a 1916 manual on how to teach this type of chopped-up, basic French to African soldiers. “In the introduction it said that because African languages were extremely ‘poor’, they had to be taught a kind of poor French … Lots of tirailleurs understood this was a means to infantilise them. There are accounts of riflemen who felt they were being mocked when they spoke it.”

Diop also wanted to capture the universal theme of the stunned silence of war. He was inspired in part by his white maternal grandfather, who came from a village in south-west France and was hit by mustard gas while fighting in the first world war. “He came home and he said nothing,” Diop explains. “He – and no doubt other soldiers, including African soldiers – were prudish about talking about it; didn’t want to relive extremely difficult events and wanted to protect their families from the horror. I wanted that silence to be filled by a voice, and by a voice that is inaudible because it’s the voice of thought, an interior voice.” The novel made such an impact in France that readers would come to signings with letters from their great grandfathers and photographs of their relatives smiling with African riflemen during the war, wishing they had asked their relatives more.

Ultimately, it is a novel about the monstrosity and savagery of war. Ndiaye is a crazed young man in the trenches, systematically and shockingly knifing enemy soldiers in the belly and chopping off their hands. But that act by one human pales in comparison to the inhuman scale of the wider war, where industrial-scale shelling ripped apart a whole generation. “It’s the war that’s savage, not the soldiers,” Diop says. He calls his main character “a monster” but adds: “at the same time he’s so human, and maybe that’s the case for all of us. We share his thoughts, we share his intimacy, but he is also someone extremely violent and traumatised by war, as lots of soldiers were.”

There is a scene in the trenches that drives home the utter futility of this war fought by the young. Mutinous French soldiers in Ndiaye’s unit are punished by being sent out of the trench to their deaths with their hands tied behind their backs. It’s a comment on how the carnage was so inevitable that it would make little difference if soldiers’ hands were tied. Diop argues that “all wars are organised by adults to kill very young people and children. I wanted to show that the world offered its youth for sacrifice to war – and it was the whole world.”

• At Night All Blood Is Black by David Diop is published by Pushkin. To support The Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.