If you know the musical “1776,” you know the plot of Joseph J. Ellis’s breezy new book. It’s a stirring and conventional story. A handful of famous men struggle to create a republic against insurmountable odds. In the long run, their greatest challenge is the problem of slavery. But the most immediate threat is the military might of Britain. Toward the end of June 1776, as the Continental Congress nears a vote on American independence, the first of 427 royal ships carrying 1,200 cannons, 32,000 soldiers and 10,000 sailors appears off Long Island. Things look dire, a point made repeatedly in the musical by a soldier bearing gloomy reports from George Washington, the commander of the Continental Army.

In Congress, the Pennsylvanian John Dickinson, a respected spokesman for the rights of British Americans, calls for delay, arguing that independence is a dangerous step in the absence of a national government and European allies. But the passion of John Adams, the wisdom of Benjamin Franklin and the eloquence of Thomas Jefferson carry the cause of independence to fruition in early July. Weeks later, Gen. William Howe and his brother, Adm. Richard Howe, eager to promote reconciliation, fail to exploit their overwhelming advantage, allowing humiliated patriot forces to escape into New Jersey. All is not lost. Out of the ashes of defeat, Americans rise committed to the national institutions that will sustain their glorious cause until the British give up and go home.

“Revolutionary Summer” achieves its major goal: to undermine the popular myth that the birth of the United States was an “Immaculate Conception,” a victory won by local militias rather than by “a standing army of regular soldiers.” Government mattered in 1776. Ellis outlines this argument through a series of individual sketches, many of them familiar to readers of his Pulitzer Prize-winning “Founding Brothers” and subtle biographies of Adams, Jefferson and Washington. No one is better at explicating the role of personal character in public life, particularly the ways in which a preoccupation with honor, or reputation, informed 18th-­century gentlemen’s approach to power.

“Revolutionary Summer,” however, purports to be a history of national origins, not a collective biography of men who apparently talked only to one another. Make no mistake: the founding fathers earned the fame they coveted by making consequential decisions. But in the summer of 1776 they were concerned about much more than the British Army. The War for Independence was also a civil war within the British Empire and an episode in a continuing conflict over the fate of North America. Ellis’s book is not wrong; it’s just incomplete and superficial. Even as he explodes the notion that volunteers won the war, he underscores an equally pervasive idea that the actions of Congress and the American Revolution were one and the same.