The Ems telegram had exactly the effect on French public opinion that Bismarck had intended. "This text produced the effect of a red flag on the Gallic bull", Bismarck later wrote. Gramont, the French foreign minister, declared that he felt "he had just received a slap". The leader of the monarchists in Parliament, Adolphe Thiers, spoke for moderation, arguing that France had won the diplomatic battle and there was no reason for war, but he was drowned out by cries that he was a traitor and a Prussian. Napoleon's new prime minister, Emile Ollivier, declared that France had done all that it could humanly and honorably do to prevent the war, and that he accepted the responsibility "with a light heart." A crowd of 15–20,000 people, carrying flags and patriotic banners, marched through the streets of Paris, demanding war. On 19 July 1870 a declaration of war was sent to the Prussian government. The southern German states immediately sided with Prussia.
On which date did France issue a declaration of war to the Prussian government?
19 July 1870