Emma's War: betrayal and death in the Sudan by Deborah Scroggins

When the southern Sudanese rebel leader Riek Machar made peace with the government in 1997 and moved to Khartoum, there was, for many, a subtext. Would Riek's English wife, Emma McCune, have gone with him, to live under a fundamentalist regime she loathed, or would she have left him?

Emma had died four years earlier, five months pregnant, in a car crash in Nairobi. She was 29, no longer the golden girl she had been when, as a young recruit to the Street Kids International charity, she had won – and broken – hearts with her beauty and enthusiasm. She was "the warlord's wife", an affront to an industry that claimed to be neutral.

Emma's War goes a long way to answering the question asked in 1997. Deborah Scroggins makes clear just how much Emma knew, and accepted, after her marriage to Riek: killings, abuse of aid, even manipulation of children. It is pointless to argue that Emma was helpless, and confused, as she was. By being there, she acquiesced.

Emma had married the charismatic, Western-educated Riek, a Nuer commander in the Dinka-dominated Sudan People's Liberation Army, in June 1991. A few months later, he split from SPLA leader John Garang to establish a rival movement which he said would be neither authoritarian nor tribalist.

Emma, in England at the time, had no forewarning of Riek's plans – on this Scroggins is wrong – and was furious. "I'll be blamed for this!" she said.

Back in Africa, Emma was confronted with evidence of the tribal animosities let out of the bottle by Riek's defection. In the Bor massacre, Nuer killed, mutilated and raped many thousands of Dinka. Shown photographs by an aid worker, very much a Garang man, she reportedly asked: "Was it a victory?" The implication is that her hatred of Garang stripped her of all sympathy for the Dinka.

Emma is dead and cannot tell her side of the story. The probability is that the question she meant was: "And my husband now?" But she was already immersed in the language, and habits, of the world she married into. At Riek's headquarters, she watched in silence as displaced members of the Uduk tribe died in droves while relief was purloined by their hosts. As her husband's men prevented the Uduk from leaving, Emma took journalists to see their suffering and write of the need for more relief.

Emma was "up to her neck in horrors". But Scroggins over-estimates her importance. Emma could, and did, influence journalists and relief workers, but she had no influence on the war, brilliantly described by Scroggins. Its horrors would not "almost certainly" have happened without her. They did, and do.

Despite acknowledging the strange beauty of Sudan, Scroggins seems unable to understand Emma's love for the country. She first saw it in 1988, as one of the first journalists to report on a famine that claimed several hundred thousand lives. Her shock is clear in her description of the dead and dying Dinka: "like a landscape painted by Hieronymous Bosch, a succession of almost inhuman figures and odd cameos set in an almost bucolic landscape".

For Scroggins, Sudan was an alien and awful country. Emma loved it.

A wider theme of the book, set firmly on Emma's slim shoulders, is the "great saving illusion" of the West and the failures of the "humanitarian international". Somalia, true, was "carelessly entered and ever more carelessly exited". A decade after Bush the father declared "we will not fail", Somalia today does not have a functioning government.

Sudan is the recipient of massive aid, and much of it fuels the war. But it is wrong to say that aid workers are merely "an imperial rearguard". Aid, like Emma, is more complicated than Scroggins would have it.

Julie Flint is a journalist and writer on Africa