Amanda Foreman, living in New York, has become accustomed to being taken for a ditz. Blonde-haired like her, dazzlingly pretty like her, and given to expressing herself with similarly hectic animation, the ditz in question is Phoebe from the television sitcom Friends. "I go into the local chemist, and I can hear people saying, 'Oh my Gaaahd it's Lisa Kudrow!'," she says, laughing. "And there's a famous Amanda Foreman, an actress two years older than me, who appears in Private Practice [an American TV show]. So whenever Amanda Foreman wants a table in a restaurant, she gets it."
When, though, will our own Amanda F be taken seriously as a historian? She's been famous for 12 years, in literary-historical circles, as the author of Georgiana, Duchess of Devonshire, which won the Whitbread Prize for Best Biography in 1998. It told the story of Georgiana Cavendish, the 18th-century beauty, fashion plate, society hostess and political operator, who became infamous through her passion for gambling and her doomed affair with the future Prime Minister, Charles Grey. Stylishly written – it was an extension of her Oxford DPhil thesis, The Political Life of Georgiana Duchess of Devonshire 1757-1806, with added romance and intrigue – it sold over 200,000 copies and hit the bestseller lists. Georgiana became the subject of a TV documentary, a radio play with Judi Dench, and later a film, The Duchess, starring Keira Knightley.
Its author became an overnight literary star. Her book reviews gobbled up and spat out established academics. At literary festivals, audiences listened entranced to her impression of Georgiana's affected speech patterns. Once, at a dinner party I attended, the bien-pensant conversation between two guests was boring the rest of us. Amanda piped up. "Does anyone," she asked, "know any Hollywood gossip?"
She never looked much like a historian. AJP Taylor, JH Plumb and Lewis Namier, it has to be said, never resembled film stars. Among the more recent crop of popular chroniclers, Simon Schama, David Starkey and Michael Wood, she stood out like a flamingo at a Rotarian dinner. At the launch of The Duchess, in 2008, Foreman so dazzled onlookers that she threatened to eclipse the lovely Ms Knightley.
Within a year of her debut, she featured in Tatler's "50 famous people under 40" feature. Somehow, they persuaded her to pose for the piece with nothing on, her modesty concealed by a tall tower of Georgiana hardbacks. The photograph showed her laughing and clearly embarrassed, rather than vampish and seductive, but it came back later to bite her well-bred posterior. For, in the wake of her richly-textured debut, a sub-genre of lesser historical works appeared.
In July 2008, the biographer Kathryn Hughes went on the attack. In an article, "The Death of Life Writing", she wrote that the biographer's skill was being devalued, and much of the blame could be laid at Foreman's door. "By choosing to be photographed nude behind a pile of books," Hughes wrote, "and by allowing her own life story to become as important as the person she was writing about, Foreman did an accidental disservice to biography in general and to young women biographers in particular." Hughes was only starting. "Since Foreman's unprecedented hit," she thundered, "photogenic young women are commissioned to produce biographies of equally camera-ready subjects, regardless of whether they are equipped to do so. The results are often intellectually slight." In April this year, David Starkey launched a bilious attack on female historians who are "quite pretty" and whose names "begin and end with A", calling their works "historical Mills & Boon". He could have meant Antonia Fraser, but his remarks seemed directed at Ms Foreman. She is, it seems, insufficiently serious for him, too.
There is, therefore, a lot riding on Foreman's new book, published next month. Is it another biography of a posh and breathless horizontale, gambling her fortune away and suffering from an awful husband? Actually, no. It's an ambitious, beautifully written 800-page narrative history of Britain's involvement in the American Civil War, called A World on Fire. Beginning with the withdrawal of Lord Napier, the British diplomat, from the legation in Washington in April 1859, and ending with the assassination of Lincoln in April 1865, the book tracks six years of conflict, tacking back and forth between the Southern states' secession from the Union, the battles and political infighting, and the chatter in London salons, where major players, like William Henry Seward (the New York senator who became Lincoln's vice-president), loved to visit, scheme and be lionised.
Ms Foreman sees the book as a hybrid of history and biography. "It's history in the round," she says. "You go in, as a reader, you're tossed into the middle, all the action is happening around you... There's an enormous cast of characters – 197, actually – and they're the dramatis personae. Obviously it's history, but it's written as Dickensian drama." She admits to being inspired by the RSC's eight-hour stage version of Nicholas Nickleby, in which an ensemble cast played all the characters.
What had inspired her to write about the US Civil War? "When I was researching [the Georgiana book] at Chatsworth, I did my best to read everything they had about the family's history. I got to the 8th Duke, Spencer Cavendish, who, when he was still the Marquis of Hartington, went to America to support the North, but changed his mind and spent Christmas Day 1862 making eggnog for General Robert E Lee and his cavalry officers. I knew then that my next project would be to find out why the heir to the greatest liberal peerage in the country thought the South had the moral advantage over the North."
Foreman, by the time she made this discovery, was well up to speed with American politics and the background to the war. Her Masters degree was Politics or Providence? Why the House of Commons voted to abolish the slave trade in 1807. Her PhD thesis was Attitudes to Race and Colour in pre-Victorian England.
The attitudes of Americans toward England in the mid-19th century is a major feature of the new book; it's a subject which fascinates its author. "The anglophobia of Americans was incredible. If you were a politician, all you had to say was 'I hate the English' and your popularity would go up 10 per cent. When politicians talk about the special relationship, it's important to remember the Americans were not our friends for a long time. For America, Britain has never been more than a strategic player and when it suits them to use us, then there's been a rapprochement. But if it doesn't suit them, you're kicked out the door. In 1860, America was like a big, spoilt teenager trying to get away from its parent."
The British, by contrast, were entranced by the Civil War. Having abolished slavery, they sided with the North against the slave-owning Southern states. But among the 50,000 British who volunteered to fight in the war, a significant minority sided with the South. Why?
"Many British people loved the South," Foreman said. "They felt it was a pre-lapsarian, pre-industrial society. You must remember at the time there was a big Young England movement, and a yearning for a time unsullied by industrialism. The South seemed ideal. And it seemed to have affinities with the English aristocracy: they liked hunting, shooting and fishing, they had grand houses. All fashionable people loved the South. It was all hype, though. Scratch the surface, and you realise they're like the Spartans – a society founded on helpless slaves."
The core of the book is Ms Foreman's indefatigable tracking-down of the records of hundreds of British soldiers who volunteered to fight in the war. "I spent two years writing to every record office and library in this country, America, Canada and Australia. Then two people read about me in the press and got in touch to say, 'I've got my ancestor's papers, and he fought in the Civil War'. It was totally cool."
It's fitting that Amanda Foreman, who chronicles the six-year Anglo-American stand-off with amazing fluency, is herself Anglo-American. Her father was Carl Foreman, the Hollywood producer responsible for bringing High Noon, Bridge on the River Kwai and The Guns of Navarone into being. He was blacklisted as a suspected communist sympathiser in the McCarthy witchhunts. Amanda was born in London in 1968 and, at the age of seven, her parents moved the family to Los Angeles. At 10, she was sent to board in England. She returned to America to do her undergraduate degree at Sarah Lawrence College in Yonkers, NY, then went to Lady Margaret Hall, Oxford, for her Masters on Georgiana. When the storm about the biography and the not-very-naked photo-shoot died down, at the end of 1998, Amanda decamped to New York to start researching the Civil War. And there she met the man who became her husband, a Malmsbury vicar's son called Jonathan Barton.
"I went to stay with my friend Vicky Ward, who is a journalist, and she invited him along on my first day there. I'd met him once before, and not liked him, in fact I thought he was rather terrible. But this time he walked in – he'd been sent to work for a bank, and it was his first day too – and bang, that was absolutely it. So I stayed." They married in 2000 "and had five children pretty quickly". The children were named, with increasing exoticism, Helena, Theodore, Halcyon, Xanthe and Hero. But Amanda has always been funny about names. Since she was young, she's been known as "Bill", a blokeish nickname for such a classy dame. It's apparently the fault of her little brother who, on hearing the word "mandible", took to saying "Amanda Bill" over and over. Oh, and Jonathan is known as "Reg". Bill and Reg. It doesn't seem right, does it?
On the morning of 9/11, she was, by spooky coincidence, on a plane bound for JFK airport. "We were due to land at 9.15am, half an hour after the first plane hit. We touched down, then took off again and flew to Logan Airport, Boston. Ours was the last plane to land at Boston before everything shut down. My husband was going crazy. I got a train back to Manhattan and, as it turned a corner, you could see this terrible pall of smoke. It was the most dreadful thing." Did she think, "This is history, happening right now"? "Yes. I wished I'd been there from the start, on the streets. It was like being at the fall of the Berlin Wall." Ask her if she wrote about the event, and the answer is a surprise. "I sent a long e-mail to George Osborne describing the scene, the relatives sticking up photographs of the missing." Why him? "He's a friend. His wife Frances is godmother to one of my children." What did he do with the e-mail? "He read it out in the House of Commons." Didn't she feel she should turn it into a proper article? "Not really," she said. "I didn't feel I needed to write anything else after that. Not when my letter's in Hansard."
Bringing up five children under five, while trying to write a half-million-word book, while your husband works until 10pm, was she admits, a strain. "It is unheard of to have five children in Manhattan," she wrote in 2007. "No nanny in her right mind will work for us, since she can get the same pay for looking after one child on the Upper East Side. We live downtown, in a crumbling brownstone. We don't own a car because there is nowhere to park. Taxis can't take more than four. How does one get a triple pushchair down two flights into the Subway? Where are Dorothy's magic shoes when you need them?"
Her days fell into an exhausting pattern. "I'd start work at 7pm, when the children were in bed, and finish at 3am. Then I'd go upstairs and cry on the stairs for 20 minutes because I was so damn tired, and then I'd sleep for four hours and get up at 7.30am to make breakfast. I told myself, 'This cannot go on like this forever. But you do it because you have to'."
Things got much worse after the arrival of the twins. Jonathan was diagnosed with non-Hodgkins lymphoma. Today, Amanda's chirpy disposition trembles under the weight of the memory. She remembers one night when she nearly lost it. "It was Christmas Eve, I took Reg out of the hospital, we drove to the country and there was a terrible storm about midnight. I was filling stockings with him, there was a terrible noise, and in the twins' room the wind had blown one of the shingles off the roof. Water was pouring through, over the twins' beds down into the dining room below. I had to get the twins out, and get buckets, but the water was coming down so fast that I had to keep emptying them... I really bawled. Reg said, 'The insurance will take care of the leak, it doesn't matter. I've got cancer – why are you crying about the leak?' I said, 'Reg, I can take the cancer. I can take the leak. But I cannot take them all at once'." Jonathan had chemotherapy, and finished treatment last year. "So it's been nearly 18 months now..."
Foreman has been watching Barack Obama closely, as he approaches mid-term elections in a storm of criticism. "American disillusionment is as American as apple pie," she said. "But what's more interesting is the breakdown of the special relationship. Almost the first thing Obama did in the White House was to return the bust of Winston Churchill to the British embassy. That suggests a major re-ordering of things. It'll be fascinating to see what happens from now on. It was a genuine break with the recent past – perhaps to re-connect with the past past." A past of blood, tears and sweat that this polymorphously charming (and serious) historian has brought to vivid, burning life.