“I held a Council at 10.45 to declare war with Germany. It is a terrible catastrophe but it is not our fault. An enormous crowd collected outside the Palace; we went on to the balcony both before and after dinner. When they heard that war had been declared, the excitement increased and May and I with David [the Prince of Wales], went on to the balcony; the cheering was terrific. Please God it may soon be over and that he will protect dear Bertie’s life [George VI, serving with the Royal Navy]. Bed at 12.00” 

– George V, diary, Tuesday, August 4 1914

The wet and cool opening to August gave way to sunshine on Sunday the ninth as the British Expeditionary Force embarked at Southampton docks for Boulogne. It was 12 days later, in the leafy lanes a little to the northeast of Mons, that they first encountered German soldiers, and the fighting began.

Private John Parr of 52, Lodge Lane, North Finchley, previously a milkman and a golf caddie at the North Middlesex Golf Club, was the first British soldier killed. Albert Mayer and Jules-André Peugeot, the first German and French, shot in a skirmish in the village of Joncherey, in...