On what date did Britain declare war on Germany following an " unsatisfactory reply " to the British ultimatum that Belgium must be kept neutral ?
On July 26 , in St. Petersburg , the German Ambassador von Pourtalès told Sazonov to reject Grey ’s offer of a summit in London , stating that the proposed conference was “ too unwieldy ” , and if Russia were serious about saving the peace , they would negotiate directly with the Austrians .