It is said that many academic historians resent David McCullough, the best-selling author of biographies of John Adams, Harry Truman, and Theodore Roosevelt, and golden voiced narrator of innumerable documentary films. Mr. McCullough learned his craft in part at Sports Illustrated magazine, and has never held a university chair. Yet he researches thoroughly, writes beautifully, and sells in copious amounts. Most academic historians can match him only on the research – where, they would point out, his work is derivative.

Mr. McCullough, some sniff, is a “popularizer.” And so he is. Selling well more than 1.5 million copies of a full-length biography of John Adams – a dour man, a failure as president – is no mean feat. He is also a two-time winner of the Pulitzer Prize, the National Book Award, and the Francis Parkman Prize from the American Society of Historians. The publication by Mr. McCullough of a book called simply “1776” – no subtitle – gives rise to great anticipation and, likely, further resentment. The result may not live up to the expectations of the author’s admirers, but it has very real merits.

Mr. McCullough’s “1776” (Simon & Schuster, 400 pages, $32) is actually not a history of that momentous year in politics; the Continental Congress in Philadelphia is almost entirely off stage. This is, instead, a military history, the tale of George Washington’s Continental Army from the last days of October 1775 through the first days of January 1777. As such it begs comparison with David Hackett Fischer’s “Washington’s Crossing,” recently awarded a Pulitzer for its account of Washington’s army during the period from March 1776 through February 1777. Mr. McCullough cites Mr. Fischer for his “friendship” and “insight” in the acknowledgements to “1776”; Mr. Fischer cited Mr. McCullough’s “extraordinary generosity” in “Washington’s Crossing.”

Readers who had the good fortune to pick up “Washington’s Crossing” may not need to plow the same ground again in “1776.” Mr. McCullough’s story, while critical to an understanding of the American Revolution, will be familiar, and very little will come as surprising. Mr. Fischer’s focus is somewhat tighter, and his writing nearly as good, and Mr. Fischer’s scholarship is stronger – although Mr. McCullough, with 48 pages of notes and 25 pages of bibliography, is no slouch.

Today we think most often of “1776” as a totem of freedom, a bright moment in the sun, the year of the immortal words of Jefferson’s Declaration of Independence. But that is not how it was lived by the American revolutionaries. On January 1, 1777, Robert Morris, finance chief of the Continental Congress, wrote to Washington: “The year 1776 is over. I am heartily glad of it and I hope you nor America will ever be plagued with such another.” That is the 1776 chronicled here – a year when the revolt nearly crumbled on at least two separate occasions.

Mr. McCullough charts the ebb and flow of the conflict: Washington’s successful siege of Boston – placing the British in such straits that the Old North Church was destroyed for firewood – capped by Henry Knox and his artillery seizing the initiative at Dorchester Heights; Washington’s inept defense of New York, including the rout at the Battle of Long Island and the disastrous and unnecessary loss of more than a quarter of his army at Fort Washington; the nimble and courageous retreat across New Jersey; and, finally, the morale-saving late-December triumphs at Trenton and Princeton after the legendary crossing of the Delaware River.

The only way to have improved the structure of this narrative might have been to begin with a full account of the Battle of Bunker Hill, the first real military engagement of the war. It significantly shaped the thinking of both Washington and British commander William Howe, and this influence is well-charted by Mr. McCullough. But instead of beginning with the battle, Mr. McCullough chooses to begin with reactions to it in London, which gets the book off to a slow start.

The greatest strength of “1776” is its nuanced portrait of the American commander, who emerges here more fully realized than in either “Washington’s Crossing” or even Joseph Ellis’s recent “His Excellency George Washington.” Mr. McCullough notes at one point that Lord Howe and his associates seem to have been remarkably uninterested in their opponent: “George Washington was rarely ever mentioned, except in passing. There was no apparent consideration of what manner of man he was, what his state of mind, his strengths and weaknesses, might be.” Mr. McCullough does not repeat their mistake.

Mr. McCullough reminds us that General Washington was not the old man we remember as president 20 years later, or even when presiding magisterially over the Constitutional Convention of 1787. He was still a man in the making. The Washington of 1776 was 43, the same age as Theodore Roosevelt and John Kennedy – the quintessential young American leaders – in their prime. Indeed, the Battle of Long Island, his first great defeat, was actually the first time he had led a force as large as an army into a full battle.

This earlier Washington was self-conscious about his own lack of formal education, “not a brilliant strategist or tactician, not a gifted orator.” He was an elitist appalled at the state of many of his troops, particularly what he called “an unaccountable kind of stupidity in the lower class of these people, which believe me prevails but too generally among the officers,” while “a dirty, mercenary spirit pervades the whole.” As a leader, Washington was not the cautious, almost imperious figure of later years, but a sometimes impetuous commander whose own council of war had to four times stop him from launching operations to resolve the siege of Boston through a head-on attack. Left to his own devices, he would have burned New York to the ground before leaving it to the British.

His strengths, Mr. McCullough makes clear, were essentially two: his deep belief in merit and his abiding commitment to the revolutionary cause. The former trait manifested itself in his early identification of Knox and Nathaniel Greene as the ablest of his lieutenants. He was also willing to listen to and rely on them – he could have overruled the council of war and charged into Boston after all – and he remained loyal to them through some very dark hours.

Beyond this, Washington was positively Churchillian in his devotion to freedom and independence. Had the retreat into New Jersey failed to save the army, he had begun talking about moving on to western Virginia, to conduct what he called a “predatory war” – what we would term a guerrilla campaign, from the far side of the Allegheny Mountains. As Mr. McCullough notes, “He knew, as the enemy had little idea, just how big a country it was.” In all, before he crossed the Delaware, while “[b]y all reasonable signs the war was over, and the Americans had lost,” his greatest gift to his country – his founding gift – was that “Washington refused to see it that way.”

Mr. Tofel is president of the International Freedom Center, the new museum and cultural center to be built at the World Trade Center site. His is author of the forthcoming “Sounding the Trumpet: The Making of John F. Kennedy’s Inaugural Address” (Ivan R. Dee).