The Second World War is Winston Churchill’s massive, six-volume history, which begins with the aftermath of World War I. Churchill served as Great Britain’s prime minister during much of World War II and thus was uniquely positioned to analyze the conflict from the Allied perspective. His insights are particularly acute for the period beginning in 1940, when Neville Chamberlain resigned as prime minister and the king asked Churchill to form a government as the next prime minister. Chamberlain agreed to stay on as leader of the House of Commons. Churchill describes his reactions after the political crisis had passed and he appreciated the enormity of his assignment:

on the night of the 10th of May . . . I acquired the chief power in the State, which henceforth I wielded in ever-growing measure for five years and three months of world war. . . . I cannot conceal from the reader of this truthful account that as I went to bed at about 3 a.m. I was conscious of a profound sense of relief. At last I had the authority to give directions over the whole scene. I felt as if I were walking with destiny, and that all my past life had been but a preparation for this hour and this trial.

In the section called “Alone,” Churchill writes movingly of the years 1940–1942, before the United States entered the war. He explains how the British air support from the Royal Air Force (RAF) aimed, but ultimately failed, to prevent the German takeover of France. Hitler understood this loss as an indication that Britain could be conquered, or that it would surrender—a development that Churchill never considered. He describes the British resources as “separate [and] aloof,” particularly in being unique features of an island state.

After rebuilding its considerable air forces, Germany initiated a relentless aerial bombardment of Southern England. These attacks were intended either as the precursor to—or as a way to eliminate the need for—a full-scale invasion. That invasion was never to come. In the ferocious Battle of Britain, RAF planes successfully defended their homeland.

Either Hitler must invade and conquer England, or he must face an indefinite prolongation of the war, with all its incalculable hazards and complications. There was always the possibility that victory over Britain in the air would bring about the end of the British resistance, and that actual invasion . . . would also become unnecessary . . .

Churchill describes the German invasion of the Soviet Union. There was considerable dissent within Germany about the best plan of attack, as the military commander-in-chief, Brauchitsch, believed that taking Moscow should be the primary objective. Hitler, however, wanted to defeat diverse forces at numerous locations, including Leningrad in the north and the Crimea and industrial sites in the far south. One decisive setback was the limited success in the siege of Leningrad, which resulted in the city being “encircled but not taken.”

Despite their fearful losses Russian resistance remained tough and unbending. The soldiers fought to the death and their armies gained in experience and skill. Partisans rose up behind the German fronts and harassed the communications in a merciless warfare. . . . Barely two months remained before the dreaded Russian winter. Could Moscow be taken in that time? And if it were, would that be enough?