On 1 July, 1916, a continuous line of British soldiers climbed out from the trenches of the Somme into No Man's Land and began to walk slowly towards dug-in German troops armed with machine-guns and defended by thick barbed wire. By the end of that day, as old tactics were met by the reality of modern warfare, there had been more than 60,000 British casualties - a third of them fatalities.
Martin Middlebrook is a Fellow of the Royal Historical Society and the author of many important books on military history including The Kaiser's Battle and The Falklands War 1982.