What the United Nations can and cannot do to keep peace and why--an assessment in the context of world history since 1944. Leading off with the example of the Six-Day War and questions arising from the UN role, the author examines the intentions of its founders--to preserve the wartime alliance and to prevent small wars in the future--and their concommitant determination, via the veto power, to prevent interference in their own affairs. The resulting world disillusion was offset partly by Vandenberg's achievements at San Francisco-the Security Council would decide procedural matters free from the veto, the General Assembly would oversee social and economic programs, could debate the business of the great powers. The Cold War dismayed idealists and strengthened doubters; but the U.N. had a key if not conclusive role in Palestine, in Korea, in the Suez, in the Congo: Mr. Fehrenbach details developments, notes practical (increasingly financial) problems and political realities. With the emergence of the Third World, the character of the U.N. changed from an alliance to neutral ground, and the conflicting concerns of its diverse membership, numerically dominated by former colonials, made positive political action very infrequent. This analysis may be questioned and some aspects were questioned when the author's adult This Kind of Peace appeared, but the more general barbs directed at that book by some reviewer seem not to apply here. This is well-written, well-organized, well-reasoned-and so much more comprehensive and realistic in covering U.N. history as to outdistance all the general juveniles.