Lions led by donkeys: The British army's Western Front generals

Most people interested in the Great War are familiar with the names of a handful of senior commanders, French, Haig, Allenby, Byng, Plumer, Rawlinson. And probably familiar with the reputations of many of them as ‘donkeys’ who sent their lion-hearted men to brutal deaths on squalid battlefields, the state of which they were culpably ignorant and from whose deprivations they were comfortably remote.

But what about the mass of general officers in an army of 60 divisions and two million men? Who were they? How many were there? How were they chosen, promoted and dismissed?