Grid: The Life and Times of First World War Fighter Ace Keith Caldwell.

Combat in the air brought a rare splash of colour to the Western Front in the First World War. In what otherwise seems to be an anonymous conflict of mass armies and grinding attrition, individual pilots emerged from the mass of khaki and field grey. The names of the most famous of them – the German Manfred von Richthofen, the Canadian William Avery Bishop, and the Englishman Albert Ball, among others – continue to resonate to the present day.