Dunant's Dream: war, Switzerland and the history of the Red Cross by Caroline Moorehead HarperCollins, pounds 24.99; Piers Brendon uncovers a dark side to the humane heroes
This big book is a masterpiece of compression. Caroline Moorehead has been given fuller access to the gigantic Red Cross archive than any of her few predecessors, and she distils the raw material into a story that is always compelling and often horrifying. In what a hideous irony, for example, were ambulances of the Third Reich's captive Red Cross organisation used to transport Zyklon-B, the gas used in the death camps. Anecdotally rich, this study is also lucidly written and full of vivid pen-portraits of leading characters. Moreover, it is sharply critical. Yet Moorehead shows that, for all its faults, the Red Cross has moved mountains to mitigate man's inhumanity to man.

The organisation was the dream-child of a young Swiss businessman named Henri Dunant, who witnessed the battle of Solferino in 1859. The carnage was appalling and the French, with four vets per thousand horses, had only one doctor for every thousand men. Dunant mustered teams of helpers to tend the wounded irrespective of their nationality - "tutti fratelli" as he put it, all brothers. His passionate account of the "sheer butchery" and his eloquent plea for the establishment of societies of volunteers to assist suffering soldiers in future conflicts won an immediate response throughout Europe.

A committee set up in Geneva created what became known as the Red Cross. Its workers, acknowledged as neutral, soon expanded their functions to include care of prisoners, aid for refugees, the tracing of missing persons and so on. In 1864 the committee formulated the first legal code, later revised, to "humanise war" - though it has never tried to outlaw it. Signing the so-called Geneva Convention was soon deemed to be the mark of a civilised state.

Yet, as Moorehead points out, the International Committee of the Red Cross (ICRC) was not international at all. It was not even a public body but a self-perpetuating private oligarchy. Its 25 members were all Swiss, male, Protestant and respectable (when Dunant went bankrupt they swiftly ostracised him). They were old-fashioned, amateurish, suspicious of nurses and contemptuous of "savages". They were also secretive, keeping their own counsel and safeguarding the confidences of errant governments in a way that almost implied complicity.

Apart from admitting a few women and Catholics, Moorehead suggests, the ICRC has scarcely changed. This is not to deny that it has pushed out the frontiers of philanthropy. It has even spoken out boldly against state- sponsored evil, denouncing Iraq's use of chemical weapons and Israel's use of torture. However, the greatest glory of the Red Cross has not been its leaders but its delegates, its quasi-independent agents in the field.

As disaster relief became the Red Cross's peace-time vocation, delegates found ways of alleviating the suffering caused by flood, famine and earthquake. They rescued bands of wild children from the Urals, secured hostage exchanges during the Spanish Civil War, beat vainly upon the gates of Stalin's gulags, risked their lives trying to help PoWs in Japanese hands, struggled to save the Jews of Hungary, had the Greek Colonels' worst prison camp shut down, searched for the "disappeared" of Chile, acted simultaneously as adventurers, doctors and priests during the Yemen's prolonged bloodbath.

By contrast, the ICRC said nothing about Mussolini's use of poison gas in Ethiopia, pretended not to know what was going on in Hitler's Germany, and wrote letters of exquisite politeness to Tokyo. The committee's vilest hour, as Moorehead demonstrates, was in 1942 when it failed to condemn the Jewish genocide, of which (like the equally reticent Vatican - a good subject for Moorehead's next book) it had irrefutable evidence. The ICRC did not even disown the Nazi Red Cross, the last head of which, Karl Gebhardt, conducted barbaric medical experiments on concentration-camp inmates, some of them children as young as six.

Since 1945 the ICRC has faced agonising new problems: the scourge of terrorism, crimes committed in the name of religious fundamentalism, the spread of small arms and anti-personnel mines, the fragmentation of states, ethnic cleansing, and vicious local wars in which civilians make up 90 per cent of the casualties (as opposed to 10 per cent during the First World War). Geneva has responded cautiously. This is not altogether surprising since, as Moorehead observes, the Red Cross symbol is now often a target rather than a shield. But failures in the massive relief operations carried out in Biafra and Cambodia prompted unrest inside the organisation. Outside it, "radical humanitarians" founded aggressive rival agencies such as Medecins Sans Frontieres, which were ready to to deliver aid without reference to those in power.

Moorehead becomes more impressionistic towards the end of her book, and it's not quite clear where her sympathies lie. But this (and a few tiny slips) apart, her biography of the peculiar Swiss institution is a triumph.