Deborah Baker's most recent book, "The Convert," was a finalist for the 2011 National Book Award

The first volume of William Manchester's biography of Winston Spencer Churchill, "The Last Lion," packed a freighted load in 1983. Subtitled "Visions of Glory, 1874-1932," it presented his lonely childhood; his early military and literary exploits in India, Afghanistan and South Africa; his precocious entry into politics and rapid rise; his equally rapid fall after the disastrous Dardanelles campaign of World War I; his abandonment of the Liberal Party; and his resignation from the Tory leadership over a difference of opinion on granting India a small degree of sovereignty.

In a second volume, Manchester planned to unleash the whirlwind of Churchill's legendary prime ministership during six years of total war, stage his return to power in 1951 and document his long, aimless decline. Instead, "Alone, 1932-1940" (1989) covered just his eight years as a political pariah, a period when he fulminated against Gandhi, wrote to make ends meet and vainly tried to get England to meet the rising threat of Hitler. Both volumes were masterly narratives, filled with close-ups and unexpectedly revealing historical digressions. But readers were left awaiting the main event, the war foreshadowed in the opening pages of "The Last Lion."

Beginning like all great epics in medias res, "Visions of Glory" had summoned that fateful hour in 1940 when nearly 220,000 Tommies faced their doom at Dunkirk—England's "greatest crisis since the Norman Conquest." The sublime mood established, Manchester continued in mock Churchillian cadences, describing the call of destiny that Winston Churchill had spent his life waiting for.

England's new leader, were he to prevail, would have to stand for everything England's decent, civilized Establishment had rejected. . . . Like Adolf Hitler he would have to be a leader of intuitive genius, a born demagogue . . . a believer in the supremacy of his race . . . an artist who knew how to gather the blazing light of history into his prism and then distort it to his ends, an embodiment of inflexible resolution who could impose his will and his imagination on his people—a great tragedian who understood the appeal of martyrdom and could tell his followers the worst, hurling it to them like great chunks of bleeding meat. . . . Such a man would be England's last chance....