The First World War was by far the bloodiest conflict in Britain's history. Yet for all the war's prominence in national consciousness, the debate on its origins has been desultory and muted. The British feel that they have little need to reproach themselves over the war's causation. Indeed, few historians have accused Britain of having instigated the war.

To be sure, that history is not without controversy. In the 1930s David Lloyd George in his memoirs suggested that Sir Edward Grey, the British secretary of state for Foreign Affairs, was culpable for failing to deter German aggression. In other words, Grey might have faced Germany down had he categorically declared, in July 1914, Great Britain's readiness to go to war if France were attacked. But such an allegation of reluctance to threaten force is hardly damning; it is surely more reasonable to attribute blame to those statesmen whose readiness to employ violence, as seen in previous chapters, was all too great.

There was another difficulty: Grey could not issue such a declaration in July – because a majority of the Cabinet, including Lloyd George, opposed intervention. A declaration by Grey would probably have brought down the government and that, for the moment at least, would have removed the deterrent threat.

Any assessment of Great Britain's part in the origins of the First World War must address several basic questions. Who made the decision to enter the war and why? Where did the “war powers” lie?