The death of Fox, according to Napoleon himself, was the immediate cause of the failure of these negotiations. The Emperor maintained that had the great English statesman lived—he died on the 23rd of January, 1806—the negotiations would have been resumed and pushed to a successful close. When the Emperor of Russia went to Berlin he offered Prussia all the forces of his own great Empire. War-like preparations of every kind filled the Kingdom of Prussia during August and September 1806. Notwithstanding the protestations made almost daily by the Prussian government, through its minister at Paris, towards the middle of August her preparations assumed such a decided character that her real object could no longer be concealed. A friendly letter was even dispatched from the King of Prussia to Napoleon and the French ambassador at Berlin was treated with due consideration but which was far from honest at heart.
On the 21st of September Napoleon wrote to the princes of the Confederation of the Rhine, requesting them to furnish their contingent troops for his army, and which was complied with, according to treaty. On the 25th the Emperor quitted his imperial residence to place himself at the head of the army. While at the theatre at St. Cloud he received a dispatch from Murat containing an account of an attack made on French troops by some Prussian detachments. "I see they are determined to try us," he said to Count Rapp and orders were immediately given to prepare for departure to the frontier. He arrived at Mayence on the 28th and on the 1st of October passed the Rhine.
On this same day the Prussian minister at Paris presented a note to Talleyrand, Minister of Foreign Affairs, an ultimatum in which Prussia demanded, among other things, that the formation of a Confederacy in the North of Germany should no longer be thwarted by French interference, to renounce the kingdoms of Holland and Italy, and that the French troops within the territories of the Rhenish league should recross the Rhine into France by the 8th of the same month of October,—a virtual declaration of war.
The conduct of Prussia in thus rushing into hostilities, without waiting for the advance of her allies, the Russians, was as rash as her holding back from Austria during the campaign of Austerlitz was cowardly. Napoleon had not patience to finish reading this document, conveying those demands, but threw it down with contempt.
Napoleon made answer to the Prussian note from his headquarters at Bamberg on October 6th. He addressed a proclamation to his army to inform them of the enemy they were about to fight. "Soldiers," said he, "the war-cry has been heard at Berlin; for two months our provocation has been increased each day ... Let us march—let the Prussian army meet with the same fate it evinced fourteen years ago on the plains of Champagne." Thiers, the eminent historian, says in his "History of the Consulate and the Empire of France under Napoleon": "It was the height of imprudence on the part of Prussia to enter into a contest with Napoleon at a moment when the French army, returning from Austerlitz, was still in the heart of Germany, and more capable of acting than any army ever was."
It was evident that Napoleon did not feel the least concern about the approaching war. He wrote to his brothers in Naples and in Holland at this time assuring them that the present struggle would be terminated more speedily than the preceding. He called upon them to observe in what manner a German sovereign still dared to insult the soldiers of Austerlitz. Napoleon was then on the German side of the Rhine in person. The Prussian Council had directed their army to advance towards the French instead of lying on their own frontier, and the army accordingly invaded the Saxon provinces. The Elector of Saxony was compelled to accept the alliance which the cabinet of Berlin urged on him, and reluctantly joined his troops with those of Prussia.
At Bamberg, on the same day he issued his proclamation to his soldiers, Napoleon said to Berthier: "Marshal, we have a rendezvous of honor appointed for the 8th; a Frenchman never fails to keep them; but as we are told that a beautiful queen wishes to be a witness of the fight, let us be courteous, and march, without sleeping, for Saxony." Napoleon alluded to the Queen of Prussia who was with the Prussian army, dressed as an Amazon, wearing the uniform of her regiment of dragoons, "writing twenty letters a day" said the first bulletin sent to Paris, "to fan the flame in all parts."
No sooner did Napoleon learn that the Prussians had advanced into the heart of Saxony than he formed his plan of campaign: and they, persisting in their advance, and taking up a position on the Saale, afforded him the means of repeating at their expense, the very manoeuvres which had ruined the Austrians in the preceding campaign. The French commander at once perceived that the Prussian army was extended upon too wide a line, thus enabling him the better to destroy it in detail. He also discovered that the enemy had all its principal stores and magazines at Naumburg to the rearward, and he resolved to commence operations by an attempt to turn the flank and seize the magazines ere the main body of the Prussians, lying at Weimar, could be aware of his movement. The Emperor quitted Bamberg on the 8th, at three in the morning, and arrived on the same day at Cronach. Every corps of the army was then in motion.
The French came forward in three great divisions; the corps of Ney and Soult in the direction of Hof; Davoust, Murat and Bernadotte towards Saalburg and Schleiz, and Lannes and Augereau upon Coburg and Saalfeld. These last generals were opposed at Saalfeld with much firmness by Prince Louis of Prussia, cousin-german to the king, who imprudently abandoned the bridge over the Saale,—which he might have defended with success,—and came out into the open plain where his troops were overpowered by the French. Fighting hand to hand with a subaltern who ran up to him and cried, "Surrender, General!" the brave young officer in brilliant uniform and adorned with all his decorations, replied with a sabre cut, and was immediately struck down by a mortal thrust in the face with a sabre, which occasioned it to be remarked in the second bulletin that "the first blow of the war had killed one of its authors."
Prince Frederick Christian Louis of Prussia had been very impatient to commence the war and urged and hastened hostilities. He was, besides, a man of great courage and talent. Rapp in his "Memoirs" says: "Napoleon, who did not like this petulant eagerness, was conversing with us one evening respecting the generals of the enemy's army. Some one present happened to mention Prince Louis. 'As for him' said he, 'I foretell that he will be killed in this campaign.' Who could have thought the prediction would so soon have been fulfilled?"