Major and Mrs Holt's Pocket Battlefield Guide to the Somme 1916/1918: The Big Push:1 July - 17 November 1916; The Kaiser's Offensive: 21 March - 25 April 1918; American/Canadian/French Sectors 1918.
Major & Mrs Holt are the Formost experts on battlefield touring.  Their previous guides books including the Somme, Ypres, Gallipoli, Normandy and Market Garden (Arnhem), Western Front North, are all bestsellers.