“A World on Fire” treats readers to a sprawling drama of British engagement with the American Civil War. Amanda Foreman builds her narrative, which she describes as “a biography of . . . the many relationships that together formed the British-American experience during the Civil War,” around a huge cast of politicians, diplomats, soldiers and civilians in Great Britain, the United States and the Confederacy. Also the author of a best-selling book on Georgiana Spencer Cavendish, Duchess of Devonshire (1757-1806), Foreman is largely unconcerned with arcane scholarly debates, writing for an audience of non-specialists drawn to engrossing accounts of major historical events.

A half-dozen individuals, some of whom wrote famous accounts, will suggest the variety of Foreman’s witnesses. Charles Francis Adams served as American minister to Great Britain — as had his father and grandfather before they occupied the presidency. Arthur James Lyon Fremantle, an officer in the Coldstream Guards, traveled widely throughout the Confederacy and was present at Gettysburg. A Washington socialite before the war, Rose O’Neal Greenhow became a Confederate spy and lived for a time in London. Francis Charles Lawley, private secretary to William Gladstone in the 1850s, contributed pro-Southern articles to the Times, and Frank Vizetelly, a war correspondent and artist for the Illustrated London News, created a memorable illustrative record. Sir Percy Wyndham, a soldier of fortune who fought for the United States, cut a flamboyant swath while campaigning in Virginia.

Foreman’s descriptive gifts show especially well in bringing vividly to life the political and diplomatic worlds of Washington and London. Although her text offers few surprises about such well-studied topics as the Trent Affair, how the loss of Southern cotton affected British textile manufacturers and workers, and maneuvers relating to diplomatic recognition of the Confederacy, it excels at deft biographical portraits and inserts readers into the drawing rooms, governmental buildings and other sites of discussion, debate and policy-making.

Foreman’s introduction of the senior British diplomat in the United States, for example, creates a memorable impression. “Even by English standards,” she notes, “the forty-two-year-old Richard Brickerton Pemell Lyons was an eccentric character. Any display of emotion — including his own — made him uncomfortable.” The fact that Lyons neither smoked nor drank “simply accentuated his strangeness” to residents of Washington. Gossipmongers speculated about whether the bachelor would succumb to the charms of an American woman, but “it was soon discovered . . . that Lyons, with his little round face and droopy eyes, was neither a Mr. Bingley nor a Mr. Darcy.” Similarly, Foreman reveals much about Charles Francis Adams in a single passage. The diplomat found little to recommend the English aristocracy, members of which returned the favor: “Those who did try to be friendly to Adams were often put off by his stiff manner. . . . Adams was incapable of producing charm on demand, a serious handicap for a diplomat.”

Great Britain never recognized the Confederacy, but the incipient republic had the best of English journalistic attention during the war’s middle years. “The combination of Lawley’s eyewitness reports and Frank Vizetelly’s emotive drawings,” states Foreman, “certainly acted powerfully on the public conscience.” Lawley highlighted Confederate suffering and forecast possible Southern victory, while Vizetelly engendered sympathy for the Confederacy with sketches of refugees camping in the woods near Vicksburg and civilians under fire from Union artillery in Charleston. Such coverage helped counter British support for the United States generated by the Emancipation Proclamation.

‘A World on Fire: Britain's Crucial Role in the American Civil War’ by Amanda Foreman. Random House. 958 pp. $35. (Random House)

Foreman skillfully handles complex attitudes toward the Confederacy among the British upper classes, which often mixed compassion for the white population with disgust at the institution of slavery. Rose O’Neal Greenhow “confused sympathy for Southern suffering . . . with acceptance of Southern slavery.” After being pressed “relentlessly on the subject of slave families” by an earl, Greenhow “lost her temper and shrilly revealed the ugly prejudice of her native country. Rose sensed the alienation of her audience and was furious. It was at moments like this that she hated the English almost as much as she hated the North.”

On the military front, Foreman gets some details wrong but deploys memorable British accounts to illuminate famous campaigns. On July 2 at Gettysburg, Fremantle recorded how, in the midst of James Longstreet’s powerful assault against the Union left flank, a Confederate band “began to play polkas and waltzes, which sounded very curious, accompanied by the hissing and bursting of shells.” The next day, “Fremantle entered the wood where [George E.] Pickett’s division had gathered only a few minutes before. Federal shells were bringing down huge tree limbs, and yet the wood was full of gray-clad soldiers, ‘in numbers as great as the crowd in Oxford Street in the middle of the day.’ Then he saw that every single one was wounded.”

Foreman’s challenge lay in bringing coherence to a narrative that in a single chapter can range from London, to the naval duel between the C.S.S. Alabama and the U.S.S. Kearsarge off Cherbourg, to Washington, to military operations in Louisiana, and back to Washington. She found inspiration in a 1980 staging of “Nicholas Nickleby” — “an extraordinary ‘theater-in-the-round’ production that brought together a vast panoply of characters through a combination of three-dimensional staging, shifting scenes, and running narratives that created an all-enveloping experience for the audience.” Foreman constructs what she terms “a history-in-the-round” that, to a remarkable degree, places “the reader inside the British-American world of the Civil War.”

A brief review can only hint at the expansive scope, rich detail and pulsing energy of “A World on Fire.” Foreman succeeds admirably in evoking the British dimension of the great American crisis.

Gary W. Gallagher , the Nau Professor of History at the University of Virginia, is author of “The Union War.“