Just off Union Square is one of the last remaining visible strongholds of the Society of St. Tammany, perhaps the nation’s greatest political machine. For decades the order used the building (now a theater) as its headquarters, from which it organized its grand processions, made backroom deals, and rallied the troops. The Union Square location, and much of the Tammany power, was due to one man, known in his lifetime and ever afterward simply as the Boss: William M. Tweed.

Tweed, born in 1823 to a chairmaker of Scottish descent, worked his way up from the hardscrabble neighborhoods underneath the Williamsburg Bridge to be the most powerful man in the city and state, and a player in national politics. In this new book (Carroll & Graf, $27.00, 438 pages), Kenneth Ackerman tells the story of the Boss and his effect on New York as the city entered the era of mass democracy after the Civil War. While it is an exaggeration to say, as the book’s subtitle does, that Tweed “conceived the soul of modern New York” (whatever that means), he did reflect the conflicted opinions of the time about democracy and the mixture of money and politics.

While this book is flawed and at times repetitive – the same characters are identified many times, and some text is even repeated – nevertheless “Boss Tweed” is a gripping read. Mr. Ackerman opens his story with the 1863 Civil War draft riots. For three days, the city was powerless to prevent looting and murder. Tweed, who had been made Tammany chairman (or Grand Sachem) just six months before, came into the spotlight. After the riots were crushed by federal troops, Tweed traveled to Washington to meet Secretary of State Stanton and present a plan for managing the draft in New York to avoid further bloodshed. Stanton agreed to the plan, which allowed an escape for poor people who could not afford the $300 draft exemption but provided a bonus for those who would serve. Tweed returned as the city’s savior.

For the next decade, Tammany and Tweed – who, aside from a brief and unsatisfying stint in Washington as a congressman, served as a city alderman and a member of the Board of Supervisors – ruled New York. Tweed dominated what Ackerman calls “the grimy reality of American politics, perfecting forms of graft and voting-box abuse” that would become bywords for corruption, while at the same time midwifing a new city into being.

Yes, Tammany stole, and stole grandly and creatively. But the story is more complicated, because it also built: Tammany supported not only the Brooklyn Bridge, but other monuments dotted throughout the city, perhaps the most grandiose being the recently reopened “Tweed Courthouse” near City Hall. Mr. Ackerman perhaps credits Tammany too much for the building program – New York’s entire economy was growing, and had surplus labor willing to do the work – but certainly the pace and scale of the building projects would not have been possible without the graft Tammany facilitated.

While sophisticated maneuvering and bribery was crucial to Tammany’s success, the other pillar on which it rested was its ability to back up its power-plays with violence. Mr. Ackerman focused not on the intimidation and street brawls that so often accompanied election season but rather the financial and political schemes that enabled Tammany eventually to concentrate all power in the city in what came to be known as the Ring: Tweed; New York Mayor Francis Oakley; city Comptroller “Slippery Dick” Connolly; and city chamberlain Peter Sweeny. No one had seen anything like the Ring before. Altogether, the Ring stole some $1 billion in today’s money, an amount so astonishing that almost until the end no one believed it.

While the Ring was unstoppable for years, they were not unopposed. Harper’s cartoonist Thomas Nash became famous in part because of his anti-Tweed drawings, and the New York Times took aim at Tweed. Both set their sights on Tweed for reasons that Mr. Ackerman does not make entirely clear. They had no evidence until a disaffected Tammany follower handed over ledger books that recorded the details of illegal payoffs, inflated bills, and no-show workers.

It is a testament to Tweed’s skill as a political leader (and of the corruption of New York politics of the time) that after he was arrested and his secret dealings were beginning to be made public Tweed nevertheless won re-election to the State Assembly. Nevertheless, the end was near. In these days of Enron and Arthur Andersen, even young lawyers know to follow the money. But in the 1870s, tracking accounting entries to find illegal payments was brand-new, and Mr. Ackerman gives us a sense of the exhilaration of the investigators, led by Reform Democrat and future New York Governor Samuel J. Tilden, as they traced thousands of dollars to Tweed’s account.

One by one, the members of the Ring either gave up or disappeared. The Boss stayed in his offices in Lower Manhattan, or his country home in Greenwich, and tried to wait it out. But Tweed was learning a lesson in modern celebrity: Once the public tide has turned, it is hard to win it back. He was tried and sentenced in 1873 to 12 years in Blackwell’s Island prison. In 1875, after two years in prison, he arranged a prison break. He was on the run for months, first to Florida, then Cuba, before heading for Spain.

Along the way, Tweed became an issue in the 1876 presidential campaign. Tilden was running against Rutherford B. Hayes, and the Boss was a centerpiece of Tilden’s record of machine-busting. He had to be brought back to prison: With the help of a compliant Ulysses Grant, who did not wish to see Hayes win, Tweed was trapped and returned off the coast of Spain. (In the end, the Boss’s capture did not help Tilden, who lost to Hayes in a hotly disputed election). Among the other members of the Ring who had escaped to Europe, only Tweed was tracked and returned.

Mr. Ackerman’s story reaches its climax with the dramatic testimony Tweed gave to the Board of Aldermen in 1877 in a last-ditch effort obtain his release from prison. His testimony – recounting hundreds of deals, thousands of payments, and naming names – shocked the city. It was all for nothing; the enemies Tweed had made prevented his release. Tweed was a beaten man, worn down by prison, poor health, and broken promises.

The element missing from this book is the Boss’s own opinions, especially on the crucial questions: What did Tweed think he was doing when he skimmed millions? Why did he stay in New York when the Ring collapsed? Tweed left few personal writings, and he comes across as an opaque figure. Tilden comes across as a humorless bluenose who used tactics unacceptable by today’s standards to keep the Boss imprisoned.

Tammany, with its Native American imagery and open graft, seems part of a New York that is no more. But Mr. Ackerman’s book also reminds us that though Tweed was brought down, Tammany only recently left us. Its last leader, Carmine DeSapio, died only in 2004, and it was only in the 1960s, when an up-and-coming politician named Edward I. Koch won victory on an anti-Tammany ticket, that Tammany finally lost its power and passed from the American political scene.

Mr. Russello last wrote in these pages on the history of Wall Street.