The long-awaited third and last volume of William Manchester's masterful biography of Winston Churchill covers the final 25 years of the subject's life - nearly as long as it took to research and write the book.

It was worth the wait.

Even if it had ended in 1940, Churchill's career was remarkable enough to justify the first two volumes that span a neglected childhood, a search for glory on the battlefield and years in the political wilderness in which he warned his countrymen about the looming threat in Nazi Germany.

For most of us, however, the years before he was appointed prime minister in 1940 merely set the stage for the Churchill we remember: the bulldoglike leader who inspired Britain during its darkest days when Hitler was master of Europe and the island nation stood alone.

Manchester had finished the research for "Defender of the Realm" when he suffered a stroke and in 2003 asked his friend, journalist Paul Reid, to complete the project. Manchester died less than two months after Reid came onboard. All told, it took more than 20 years for the nearly 1,200-page book to see the light of day.

Happily, the collaboration completes the Churchill portrait in a seamless manner, combining the detailed research, sharp analysis and sparkling prose that readers of the first two volumes have come to expect.

The focus, of course, is World War II, and the book doubles as a history of the conflict. Shocked by the swift fall of Singapore - Churchill called it "the greatest disaster in our history" - he was buoyed less than nine months later by the tide-turning victory at El Alamein. Along with the battles, the authors provide vivid accounts of the prime minister's meetings with Franklin Roosevelt and Joseph Stalin, where we see Churchill's role diminish to that of third fiddle among the Big Three as his concerns about the Soviet dictator's designs on eastern Europe prove to be prophetic.

Throughout the book, Churchill comes across as a man of action, an energetic leader with an indomitable spirit whose strength and vitality belie his age. His prodigious drinking and late-night work schedule didn't appear to hamper his effectiveness, and the authors reject the notion that he suffered from depression, or what Churchill called the "black dog."

He found the war "exhilarating," viewing it as "the supreme chapter" of his life. He was drawn to the battlefield; he sought to get close to the action at critical times such as D-Day and eagerly visited anti-aircraft crews and bombed-out sections of London during the Blitz. But his words proved to be his mightiest weapons, inspiring Britons when they fought alone. His tribute to his nation's fighter pilots who won the Battle of Britain - "Never in the field of human conflict was so much owed by so many to so few" - retains its power today. "Certainly he demonstrated that powerful words could alter the course of history," the authors write.

Readers who might be put off by the length of this doorstop of a book need not worry. This is popular history at its most readable and absorbing. It captures the drama of the war years and the leading players while providing a balanced and memorable portrait of the man viewed by many as the 20th century's greatest statesman.