For the second year running, the £30,000 Orange Broadband prize for fiction has been awarded to a young writer already acquiring prodigious literary celebrity.
Two years younger than last year's winner Zadie Smith and with one book fewer under her belt, Nigerian-born Chimamanda Ngozi Adichie, 29, took it for her domestic epic of the Biafra war, Half of a Yellow Sun.
Her triumph vindicated the readers who have bought 187,000 copies since the paperback was published in January, and the bookmakers William Hill who made her odds-on favourite at 13/8.
Although she was up against this year's Man Booker prize winner, Kiran Desai's sumptuously written The Inheritance of Loss, and a highly rated US bestseller, Anne Tyler's Digging to America, Adichie's saga inspired a rare unanimity. This held firm both among the judges and the readers who voted for it via text messages to the prize website.
The judges' chair for the women-only contest, the writer and broadcaster Muriel Gray, said they were "hugely impressed by the power, ambition and skill of Chimamanda Ngozi Adichie's novel. It's astonishing, not just in the skilful subject matter, but in the brilliance of its accessibility. This is a moving and important book by an incredibly exciting author. "
Half of a Yellow Sun - Adichie's second novel - is her homage to "the tiny debris of passionate courage", her fellow Nigerian writer Chinua Achebe's phrase for the Biafran victims of the 1967-1970 Nigerian civil war. Born seven years after it ended, she lost both her grandfathers among the many thousands of civilian dead. Achebe himself has joined a chorus of praise for the novel, calling Adichie " a new writer endowed with the gift of ancient storytellers".
Posters market her narrative, which had the sales boost of selection for Channel 4's Richard and Judy book club, in the style of a Hollywood film. Yet it takes place quietly in kitchens and living rooms, with all the violence, battles and atrocities offstage.
The story follows five people through the deluded hopes and terrors of Biafra, and is focused around three principal characters: an educated young woman, her houseboy, and her sister's English lover.
Adichie's father was Nigeria's first professor of statistics and her mother the country's first female registrar. Her first novel Purple Hibiscus was recognised as showing exceptional promise.
It was shortlisted for the Orange in 2004 and won the Commonwealth writers' best first book award.
Rodney Troubridge, fiction specialist for the bookshop chain Waterstone's said: "We are delighted that a novel set in Africa with such important and relevant things to say about our ability to initiate and survive the horrors of war has won".
The prize founder Kate Mosse, noting that another war story, Karen Connolly's The Lizard Cage had won the Orange award for new writers, said: "Because everything is so terrible in the world, perhaps there is a hunger now for serious books about war explored through fiction."
The two shortlisted titles believed to have come closest to beating Half of a Yellow Sun are The Inheritance of Loss and the Chinese author Xiaolu Guo's tender romantic comedy A Concise Chinese-English Dictionary for Lovers. The latter's sales are so far relatively small since publication in February, but there are hopes in the trade that it could duplicate the success of A Short History of Tractors in Ukrainian, which won few awards but has so far sold 757,000 copies.