By Bernard Cornwell

Viking. 405 pp. $18.95

"Redcoat," a new novel by Bernard Cornwell, is a rousing adventure yarn set during the American Revolution, specifically the eight-month period from the fall of 1777 to the spring of 1778 when Sir William Howe and the British occupied Philadelphia. The largest city in America, still filled with Loyalists who could be rallied to the flag, it was a prize worth having. Besides, Howe liked it. Bringing his mistress down from New York, he settled in for a winter of parties and good cheer.

Cornwell tells the story of that winter by setting in motion at least four lines of plot. Two of his stories -- one American, the other British -- wind through High Society, while a second pair takes us Below Stairs. One of the difficulties of the book, though not a crucial one, is that none of these separate narratives ever quite takes over, so that, as they interweave, we're sometimes not exactly sure where we are; but they do serve the author's purpose of giving us a picture of the conflict from every angle.

Sam Gilpin, the "redcoat" of the title, has joined the king's army and now must pay the price: blood and guts, flogging, a brutal life of forced marches and penny whores. Above him is the world of the British officer, the court that swirls around General Howe. Here we have Captain Vane, elevated by "Good-Natured Billy" from the ranks, but soon consumed by ambition: This will take the form of a brutal investigation of Martha Crowl, a rich Philadelphia matron who's spying for Washington.

In turn, we see the world of the colonies' "aristocracy," a world now much divided. Martha is passionate for Liberty, but her uncle, Abel Becket, is a Tory who refuses to "fight for some dreamer's madness called independence." Abel's young nephew, the cripple Jonathon, makes the last link, for he has fallen in love with a farm girl, Caroline Fisher, who lives among the river men and small traders of the Delaware. Naturally, the separate fates of all those characters come together, though I don't want to spoil Cornwell's story by saying exactly how.

I learned a good deal from this book. Cornwell obviously has a passion for military history, and his battle scenes are excellent. The book begins with a brutal description of the massacre at Paoli's tavern, where "No-Flint Grey" literally caught the Americans napping. And the battle at Germantown is very well done; the roar of the muskets and the famous fog (some of Washington's men fired on each other) don't obscure the broader picture of what's going on.

About larger matters, he also displays a good sense of perspective. His choice of this particular episode as the center of his book is itself instructive. Howe's occupation of Philadelphia was certainly important, but in comparison with other campaigns and battles, it was something of a sideshow. This, however, is part of Cornwell's point: to show how reluctantly the British committed themselves to the war, and how unimportant it was in the world at that time. One of Washington's generals, Charles Lee, was apparently Howe's captive over the winter, and at one point he wonders aloud why he bothers to fight for the rebellion at all. "Why do you?" asks Howe, and Lee shrugs: "To get my name in the history books, I suppose." To which Howe replies, "You think history will remember such a little war?"

Still, despite all this in Cornwell's favor, it's important to note that this book never quite manages to leap the divide that separates costume drama from the true historical novel -- there's one large matter he doesn't get right. That is motivation, of course. What kind of history did Lee, Washington and the others really believe in? Why did they fight? In the narrative, Cornwell's characters are most commonly linked by soap opera "love," and though words like "Liberty" crop up fairly often, they are only words. The religious ideals and political passions that these people felt are absent, so that this is a book about the American Revolution that contains no ideas. And even today, when America's greatness resides in her power, it is the ideas that make the history worth reading. The reviewer is the author of "The Red Fox." His next novel is titled "China Lake."