Emanuel Leutze’s painting Washington Crossing the Delaware, which hangs in New York’s Metropolitan Museum of Art, is inspiring. It was painted 75 years after the event but contains within it all the seminal features of the strugglin­g birth of the American republic.

There is a determined George Washington, commander of the Continental Army, with the Stars and Stripes prominent behind him. There are the ragge­d soldiers of the revolution pushing through the ice flows of the Delaware River.

Leutze’s painting is romanticised but is close enough to the truth to resonate still.

This is easily the best book on American political culture published this year.

It was Christmas Day in the year of the birth of the American republic, 1776. Washington’s threadbare army of about 2000 troops, many of whom lacked boots in the snow, was drawn up on the banks of the river to hear Tom Paine’s latest and most moving essay, the first pamphlet in a series known as The American Crisis, published in revolutionary Philadelphia a few days earlier. Paine’s essay began: “These are the times that try men’s souls.”

Washington’s surprise assault overwhelmed British forces, together with their German ­mercenaries, at the decisive battles of Princeton and Trenton that Christmas.

Such inspiring episodes display the American soul for it is emblematic of not only courage but also of sacrifice for a greater purpose than any individual ambition.

After all, as F. Scott Fitzgerald observed, America was neither merely a land nor a countr­y. It was an idea.

It is this spirit to which Pulitzer prize-­winning historian Jon Meacham consistently refers in his new book, The Soul of America: The Battle for Our Better Angels.

This is easily the best book on American political culture published this year.

Meacham, a visiting professor at Vanderbilt University, refers in the title to Abraham Lincol­n’s first inaugural address in which the embattled president appealed to his southern countrymen to avoid a civil war:

Though passion may have strained it must not break our bonds of affection. The mystic chords of memory, stretching from every battlefield and patriot grave to every living heart and hearthstone all over this broad land, will yet swell the chorus of the Union, when again touched, as surely they will be, by the better angels of our nature.

Meacham digs deeply into an American histor­y that he understands and acknowledges.

But time and again he shows how creative and determined leadership, especially in the White House, deliver­s extraordinary progress.

He rever­es the great figures whose leadership has delivered so much progress, especially on the issues of liberty and equality, from Linco­ln to Martin Luther King Jr; from Theodore Roosevelt to Lyndon Johnson.

He does not baulk at the darker episodes in the republic’s evolu­tion, especially in the era of reconstru­ction following the civil war.

But time and again he shows how creative and determined leadership, especially in the White House, deliver­s extraordinary progress.

Nor does Meacham think that the challenge to embrace the better angels of American natur­e is over.

The tensions of earlier times that produced the toxic extremism of the Know Nothings or the Ku Klux Klan, or Charles Lindbergh’s America­ Firsters, are again apparent:

The fires of fear in America have long found oxygen when broad, seemingly threatening change is afoot. Now, in the second decade of the new century, in the presidency
of Donald Trump, the alienated are being mobilised afresh by changing demography, by broadening conceptions of identity, and by an economy that prizes Information Age brains over manufacturing brawn.

David Duke, a former Grand Wizard of the KKK, said this at a recent white nationalist rally in Charlottesville: “We are determined to take our country back. We are going to fulfil the promises of Donald Trump. That’s what we believed in, that’s why we voted for Donald Trump.”

The fact a Klansman can endorse the President rightly may cause alarm in more than a few quarters, but Meacham, whose bio­graphies of Thomas Jefferson, Andrew Jackson­ and George HW Bush have been widely­ acclaime­d, is ­relentless in his optimism about the American future as he draws on its stor­ied past. In particular, race looms large in the narrative, which is skilfully woven and undeniably convincing in its analysis and conclusion.

The scourge of Joseph McCarthy is a telling case in point. McCarthy was a junior senator who manipulated and corrupted American anti-communist sentiment in the early post-war years of the 1950s. His outrageous allegations against public figures of impeccable reputation, including General George C. Marshall and secreta­ry of state Dean Acheson, brought ­McCarthy headlines and notoriety. It also ­instilled a fear in American public life, forever damned as McCarthyism.

Eventually, in televised hearings, his brutal smearing was challenged by counsel for the US Army, Joseph Welch, with the memorable phrase: “Have you no sense of decency, sir?”

The watching American public was aghast, and the US Senate, led in part by Prescott Bush, father and grandfather of future presidents, censured McCarthy for his misbehaviour.

Curiously, perhaps the best assessment of McCarthy was that of his close confidant, Roy Cohn, also a mentor to Trump. Cohn concluded that McCarthy was simply overexposed by the new technology of television. The public would “eventually lose interest in him and his cause”. When McCarthy “had nothing to offer but more of the same. The public sought new thrills … The surprise, the drama, were gone.”

Prophetic, perhaps?

Meacham does not gloss over the abuses of extreme groups, from the poisonous John Birch Society on the right, to violent anarchism in the 1920s on the left, but his view on the American soul is unfailingly uplifting, especially the signif­icance of the presidency.

The critical argument of his book may be distille­d in a quote from Eleanor Roosevelt: “It is essential that we remind ourselves frequently of our past history, that we recall the shining promise that it offered to all men everywhere who would be free, the promise this it is still our destiny to fulfil.” Meacham achieves this impera­tive brilliantly.

The Soul of America: The Battle for Our Better Angels
By John Meacham
Random House, 402pp