The reader that David McCullough imagines peering over his shoulder as he crafts his meticulously researched histories and biographies is the person he happens to be writing about at the time, whether it’s John Adams, Harry Truman or some anonymous soldier in a long-forgotten battle. “This has been true of everything I’ve written,” the 71-year-old Pulitzer Prize winner tells BookPage from his home on Martha’s Vineyard. “I try to write a book so that if they could read it, they would say, yes, he got it.”

McCullough’s ghostly audience this time around would include the American rebels, British regulars and their leaders who clashed with each other during the second year of the Revolutionary War. The book is titled simply 1776. It begins with the siege of Boston, an American triumph; continues through the struggles for New York in which the British forces prevailed; and ends with the American resurgence in the wintry frays at Trenton and Princeton, New Jersey.

McCullough chose to focus on 1776 “because that was the low point of our fortunes, not just in the war, but, I think one can say, in the whole history of the country. The prospects of there even being a United States of America were never more bleak. Also, it was the year of the Declaration of Independence. When I was writing the John Adams biography and trying to understand everything that was going on in Philadelphia that summer of 1776, I realized, perhaps more than I had before, that all they were doing there was theoretical and that the Declaration itself would have been nothing but words on paper had it not been for the people out fighting the war. Everything depended on them.”

While much of McCullough’s account is involved in showing how the reluctant George Washington developed into an effective military leader, it is just as attentive to the importance of lower-ranking officers and foot soldiers on both sides of the conflict.

“I think too little has been written about the British in the Revolutionary War,” he says. “A lot of what happened with those in the British army and those who were trying to manage the war in London has not been fairly understood.” To understand it better, McCullough traveled to London and pored through such primary sources of the period as letters, diaries, newspapers and magazines.

“I tried to soak up [the British magazines] if only for the vocabulary,” he says. “I [didn’t] want to be influenced by what other historians are writing now. I respect what they’re doing, and I read much of it. But I’m finding my way into that other time and into the lives of those other people through material that came from that other time and from those other people.”

McCullough was determined to give the much-maligned King George III his due. The monarch’s initial response to the American rebellion, he shows, was measured, cautious and hopeful for a peaceful resolution. Moreover, the king was a man of considerable taste and talent. “I went to see an exhibit of [his] collection of art,” says McCullough, “which included his own paintings, which are wonderful. I had simply read that he was interested in art, but when you see what he actually did himself mostly architectural drawings they’re superb.” The fact that Britain lost the war and that the king went insane many years later, McCullough thinks, helped to make George such an object of derision.

Equally diligent in researching American particulars, McCullough says he followed the path of the rebel army from Boston all the way south. “That’s also the fun of the work,” he observes. “Very often I will write the chapter, at least the first draft, before I go to look at [the actual scene] to see how closely I’ve come to getting it right. And always always there are certain things that are different from what I thought. For example, Fort Washington, which is a big part of the story. When you say it’s up above the Hudson River it is, but when you go there, it is really up above the Hudson River. You understand why [the Americans] thought it was impregnable. I felt it. I don’t think you can know anything unless you feel it. I thought, My god! If I had a fort up here, I would know damn well it could hold out. Nobody could come up those cliffs. Of course, they did.”

Tales of American courage and fortitude abound in 1776, but McCullough also presents the rebel army’s deficiencies. “Obviously, there were a lot of people who just couldn’t take it and [who] thought it was hopeless and more than anybody should be asked to do. And so they deserted by the thousands or, when their enlistment was up, they went home by the thousands. They all weren’t heroes by any means.” In addition, he points out, thousands of colonials remained loyal to the crown: “It wasn’t just a theoretic displeasure with the Revolution. They were really against it and willing to fight against it.”

Calling it the most important war in our history, McCullough says he thinks Americans tend to overlook the Revolution for one simple reason: there are no photographs of it. “We see photographs of the people in the Civil War and photographs of the carnage at Antietam and Gettysburg in Matthew Brady’s photographs. We can identify with that. Those are real people. But the people of the Revolution are so often pictured in our minds because of paintings we’ve seen as characters in a costume pageant. There’s something not quite fully real about them. And the other thing people think is that the loss of life was relatively small. Well, by 20th-century terms, of course, it was very small. But in proportion to the size of population at the time, it was enormous. If we lost a comparable number of Americans in a war today as we lost in the Revolution, we would lose about three million people.”

McCullough says it took him about four years to research and write 1776. At the moment, he has no other books in the works. “I’m trying to calm myself,” he says with a chuckle.

Edward Morris is a writer in Nashville.