1943 was the watershed year for Bomber Command s ever-escalating strategic air offensive against Germany. As the authors of this second in the four-volume official history of the bomber offensive point out, in the first three months of that year the average number of bombers available to the RAF for operations against Germany almost doubled from 500 to 974, including nearly 600 of the new, fast and heavy Lancaster bombers. At the same time, British aircrew were augmented by the Dominions - chiefly Canadians, Australians and New Zealanders. By January 1945, 46 percent of Bomber Command s pilots came from the Dominions - over half of them Canadians. 1943 was also the year when the USAF joined the offensive, and, although their unescorted daylight raids on selected targets suffered a fearful casualty toll from German fighters, they set the pattern for future combined Anglo-American operagtions against Germany. The authors also examine the splits that opened up between the three men directing the offensive - Sir Charles Portal, the Chief of Air Staff; Sir Arthur Harris, head of Bomber Command; and General Eaker, the head of the Eighth US Air Force. The Americans advocated strict selection of targets, while Harris backed all-out area attacks on such targets as Hamburg, the Ruhr and Berlin. For most of 1943, the authors argue, allied co-operation was replaced by competiton between the two schools of thought. Portal s Air Staff eventually backed the Americans, directing Bomber Command to hit targets producing German planes and aircraft parts. One result was the RAF s raid on the Schweinfurt ball bearings centre in February 1944. Another precision target examined here was 617 Squadron s famous Dambusters raid. As effective long-range allied fighters came into service to protect the US day bombers, the Combined Allied bomber offensive really began in early 1944. However, hopes that bombing alone would be enough to cripple the German war effort proved, the authors admit, completely abortive . In fact German armamants production actually increased by leaps and bounds under the skilful direction of armaments minister Albert Speer. As a result, the book concludes with an attempt by the authors to gauge the effects of Harris area bombing offensive. Well Illustrated with 15 maps and 35 photographs of aircrew, aircraft, bomb damage etc.