David Diop has become the first French novelist to win the International Booker prize for translated fiction with At Night All Blood Is Black, his first novel translated into English.

Diop, the author of two novels, and his translator Anna Moschovakis, split the £50,000 annual prize, which goes to the best author and translator of a work translated into English. At Night All Blood Is Black follows Alfa Ndiaye, a Senegalese soldier fighting for France in the first world war, whose descent into madness after the death of a childhood friend on the frontline begins to show itself in extreme brutality against enemy German soldiers in the trenches.

Approximately 135,000 Senegalese tirailleurs fought in Europe, with 30,000 killed. Diop was inspired to write the book by his Senegalese great-grandfather’s silence about his time in the war. “He never said anything to his wife, or to my mother, about his experience. That is why I was always very interested by all the tales and accounts which gave one access to a form of intimacy with that particular war,” he recently told the BBC.

Chair of judges, the historian Lucy Hughes-Hallett, called At Night All Blood Is Black “an extraordinary novel”.

“The book is frightening – reading it, you feel you are being hypnotised,” Hughes-Hallett said. “Your emotions are all jangled up, your mind is being opened to new thoughts. It is an extraordinary piece of narrative, very powerful, very compelling. The protagonist is accused of sorcery and all of us, we judges, did feel this book had somehow put a spell on us. It is that hypnotically compelling.”

She described it as “a story about war, but also about love, the comradeship of those young men who fight together and the extraordinarily intense relationships that are formed by people who are risking death alongside each other. It is also a story about language – the protagonist does not speak much French, so it is a story written in French, which we read in English, about a man thinking in Wolof. Diop has done something very clever in creating a kind of incantatory language that somehow conveys that sense of what it is like to think outside your own language, as it were.”

She said that she hoped the violence would not put off prospective readers. “You can read the last act of King Lear when the bodies are piling up on stage and still be responding not just to the horror but the great beauty of the language,” she said.

“This book does what the best poetry does, entering the reader’s consciousness at a level that bypasses rationality and transcends the subject matter. So yes indeed, you are reading about horrible mutilations and a soldier going mad … but all the same, the whole tragedy relies on this dichotomy, of the awfulness of what you are being told and the beauty of how it is being expressed. So there is a great deal of pleasure to be had from this novel.”

Born in Paris in 1966, to a French mother and Senegalese father, Diop spent his childhood in Senegal before returning to study in France, becoming a professor of 18th-century literature at the University of Pau. Since it was published in 2018, At Night All Blood Is Black has been a bestseller in France where it was shortlisted for 10 literary prizes and won the Prix Goncourt des Lycéens. Its translations have also won Italy’s Premio Strega Europeo and the Netherlands’ Europese Literatuurprijs.

At Night All Blood Is Black was picked as the winner of the International Booker from 125 submitted books. Hughes-Hallett said that many of the books submitted this year, including Diop’s, examined colonialism or migration, “which is of course the sequel to colonialism,” she said. “That story about people moving around the world, maybe being welcomed by their new host countries or maybe being kept out, is one that a lot of the authors wanted to address.”

Diop made the six-book shortlist last month alongside books including Benjamín Labatut’s When We Cease to Understand the World, translated from Spanish by Adrian Nathan West, and Maria Stepanova’s In Memory of Memory, translated from Russian by Sasha Dugdale.

Hughes-Hallett said Diop won by “majority decision” among the judges, who also included Guardian journalist and author Aida Edemariam, novelist Neel Mukherjee, historian Olivette Otele, and poet and translator George Szirtes. “I do not want to go further than that, as all six shortlisted authors were fantastic and I think it would be very invidious to go any further than to say that Diop’s book and Moschovakis’ translation were seen by a majority of us as the outstanding book,” Hughes-Hallett said.

Diop is the first French author and the first of African heritage to win the International Booker. In 2006, Nigerian author Chinua Achebe won the prize’s previous iteration, the Man Booker International, when it was a lifetime achievement award.

Diop and Moschovakis were announced as the winners in a virtual celebration live streamed from Coventry Cathedral on Wednesday night. Previous winners include South Korea’s Han Kang and Polish Nobel laureate Olga Tokarczuk, with winning authors enjoying an astronomical increase in sales after the prize.