Germany's invasion of Belgium on 4 August 1914 quickly prompted allegations of 'war crimes'. Some of them were confined to excesses committed in the military conflict - witness, for example, a captured German soldier's diary describing how British POWs were beaten to death. The Times - owned by the staunch Germanophobe Viscount Northcliffe - ran an almost certainly apocryphal story in May 1915, detailing how Allied troops in the 2nd Battle of Ypres had discovered the body of a Canadian soldier crucified on a barn door with German bayonets.

But the accusations of atrocities committed against civilians in occupied Belgium were far more damaging to the German cause. During the autumn of 1914, the British Foreign Office received a number of disturbing 'eyewitness' accounts from fleeing British subjects and Belgian refugees. German soldiers, it was alleged, had been seen 'pillaging and looting'. As reprisals for civilian attacks on the German army, they were committing 'wholesale massacres of innocent women and men' (source: FO 371/1913).

Charged by a genuine sense of moral outrage, and with one eye on the propaganda war, the Asquith government appointed a special committee to investigate these rumours in December 1914. Under the leadership of the widely respected Lord Bryce, the Committee of Alleged German Outrages published its findings five months later. The 'Bryce report' concluded that German troops had committed excesses against Belgian civilians as part of a conscious strategy of terror. It accused German soldiers of (among other things): raping women and girls; using civilians as 'human shields' during combat; and cutting off children's hands and ears in front of their horrified parents.

The Bryce report's sensational findings were published with powerful effect in neutral countries such as the USA. German attempts to counter this, by disseminating details of atrocities committed by Belgian civilians against their own soldiers, had little impact. Taken alongside the Zeppelin raids, the use of poison gas, the sinking of the Lusitania in May 1915 and the execution in Brussels in October 1915 of the British nurse Edith Cavell, the Bryce report seemed to confirm the brutal nature of German war strategy.

As a credible legal enquiry, however, the report left much to be desired. Many of the 1,200 depositions that the investigation heard (from Belgian refugees and Allied soldiers stationed in Belgium) were not taken under oath. Little attempt was made to verify some of the more fantastic testimonies. The enquiry's other main source, captured German war diaries, contained no evidence of the horrific crimes against women and children that were published in the report in May 1915.

German politicians argued, with some justification, that Britain and its allies were in no position to take the wartime moral high ground. Entente forces carried out air raids of their own on German cities, used poison gas in battle on the Western Front and executed two German nurses in circumstances similar to those surrounding Edith Cavell. Moreover, the Royal Navy's trade blockade of Germany between 1914 and 1918 caused hundreds of thousands of civilian deaths through starvation.

The line separating 'good' from 'evil' in the First World War was not clearly drawn.