Sir Alan Brooke (1883-1963), later Lord Alanbrooke, was Chief of Britain's Imperial General Staff (CIGS) during World War II--the military rein on Churchill's impetuosity and willfulness. To readers of Wig II histories, he is also known as the often-acerbic author of the diaries on which Arthur Bryant's The Turn of the Tide and Triumph in the West are based. And that, in an unusual way, is a major reason for Fraser's biography: the diaries, he feels, reveal Brooke's inner despair, not his outward strength. (At the same time, Fraser is at pains to establish the ""stern, uncompromising"" Brooke's gentle qualities in private life.) Another mainspring of the book, however, is Fraser's awareness, as a recently retired senior British officer, of the several ""dimensions"" of Brooke's wartime role--his simultaneous involvement with long-range Allied strategy, with current operations, with superiors, colleagues, and subordinates. After sketching in Brooke's atypical upbringing--in France, as the late-born ninth son of Anglo-Irish aristocrats--he concentrates, welcomely, on salient topics and episodes. Brooke's blooding at the Somme and at Dunkirk, which underlay his opposition, later, to a hasty return to Europe. His WW I mastery of ""the artillery art,"" source of his respect for other expertise. His pragmatic support for mechanization, in the '30s debate (despite his sympathy, as a horseman, with the cavalry). His varied pre-WW II commands--of the first Mobile Division, of antiaircraft forces, of the Army's Southern Command. His immediate perception, at the war's outset, of impending French collapse (the ""disgruntled and insubordinate looks"" on the soldiers' faces) and his opposition, thereafter, to further British troop commitment--""the only time"" when Churchill, argued down, said ""I agree with you."" The stormy relationship between these two, and the testy relationship between Brooke and his American counterparts, dominates the years, from December 1941, when he was CIGS. 1942 is in all respects illustrative. At Washington, in June, it was Churchill who had the ""grand strategic vision"" to propose a North African campaign to FDR as preliminary to an invasion of Southern Europe--thus reconciling Marshall's objection to a diversion of forces from Germany (""he was right"") and Brooke's overriding fear ""of a premature and unsuccessful return to the mainland of Europe"" (proven correct by, among other things, the disastrous Dieppe raid). At Cairo, in October, Brooke alone and unflinchingly made the ""momentous decisions"" to replace Auchinleck with Alexander, and to put Montgomery in charge of the Eighth Army. At Moscow, days later, he witnessed the first wary meeting between Churchill and Stalin--and was, thinks staunchly anti-Soviet Fraser, less taken in. Without unfairness or loss of balance: the effect of a featured player on a complex network of world events.