At 07.30 hours on 1 July 1916, the devastating cacophony of the Allied artillery fell silent along the front on the Somme. The ear-splitting explosions were replaced by the shrill sound of hundreds of whistles being blown. At that moment, tens of thousands of British soldiers climbed out from the trenches on their part of the Western Front, and began to make their way steadily towards the German lines opposite. It was the first day of the Battle of the Somme. By the end of the day, a number of the regiments involved had met with some degree of success; others had suffered heavy losses for no gain, whilst a few quite literally ceased to exist. That day, the old infantry tactics of the British Army clashed head-on with the reality of modern warfare. On what is generally accepted as the worst day in the British Army's history, there were more than 60,000 casualties - a third of them fatal. In this publication, the authors have drawn together, for the first time ever, all the War Diary entries for 171 British Regiments that went "over the top" that day - a day that even now still touches so many families both in the United Kingdom and around the world. The result will be a vital work of reference to the events of 1 July 1916, a valuable information source for not only for those interested in military history, but genealogists and historians alike.