Scarcely had the Emperor entered Paris after his return from the coronation in Italy, before he learned that a new coalition had been formed against him, and that England, Russia, Austria and Sweden, with half a million men, were preparing once more for war. The objects proposed were, briefly, the independence of Holland and Switzerland; the evacuation of Hanover, and the north of Germany by the French troops; the restoration of Piedmont to the King of Sardinia; and the complete evacuation of Italy by France. Great Britain, besides affording the assistance of her forces by sea and land, was to pay large subsidies for supporting the armies of the coalition. Napoleon had, in a great degree, penetrated the schemes of the allied powers, but was not prepared for the sudden assumption of arms by Austria without any declaration of war; a measure which Austria justified by referring to the increasing encroachments of France in Italy.
As the Emperor desired leisure to prosecute and perfect the great public works he had begun, or projected, he most earnestly wished for peace, and he again addressed a letter to the King of England, and which was treated with contempt. An envoy was sent to Frankfort-on-the-Main to ascertain definitely whether Austria really intended to trample another treaty in the dirt, and so soon after the fatal day at Marengo. The messenger soon returned with the best maps of the German Empire, and opening them on the council table of the Tuileries, said: "The Austrian general is advancing on Munich: the Russian army is in motion, and Prussia will join them."
The Emperor of Russia had pushed on to Berlin to win over the Prussian monarch to the great Bourbon coalition, and to make the compact more impressive, he asked his royal brother to visit with him the tomb of Frederick the Great. They descended by torchlight to the vault, and there, over the honored dust of Frederick, Francis, his heir, took a solemn oath, as he pointed to the sword of his ancestor as it lay on the coffin, to join the European coalition. Some weeks afterwards Napoleon visited the tomb as a conqueror, and said to his attendant, as he seized the precious relics: "These orders and sword shall witness no other such scene of perjury over the ashes of Frederick!"
The young Emperor of France now gathered his eagles to lead them toward the Danube. To the French Senate, whom Napoleon informed of the hostile conduct of Russia and Austria, the Emperor said: "I am about to quit my capital to place myself at the head of my army in order that I may render prompt assistance to my allies, and defend the dearest interests of my people.... I groan for the blood which it will cost Europe; but it will be the means of adding new lustre to the French name." Another campaign against the kings of Europe was inevitable, and he proceeded to achieve the destruction of Mack's army, not as at Marengo by one general battle, but by a series of grand manoeuvres, and a train of partial actions necessary to execute them, which rendered assistance and retreat alike impossible.
The great army that had been assembled on the coast of France to invade England was now relieved from its inactivity and directed to march upon the German frontiers. The Count de Ségur, who had command of the detachment of the Guard at the Tuileries, and accompanied Napoleon on this campaign, relates in his "Memoirs" a remarkable scene in the Emperor's private quarters at Boulogne before Napoleon started for the frontier. The Emperor had just received news that Admiral Villeneuve had taken the French fleet to Ferrol and left the channel. On learning this the Emperor at once decided that the contemplated invasion of England was then impossible. Ségur then says: "Sit there," Napoleon said to M. Daru, then acting as intendant-general of the army "and write." And then, without a transition, without any apparent meditation, with his brief and imperious accent, he dictated to him, without hesitation, the plan of the campaign of Ulm as far as Vienna! The army of the coast, fronting the ocean for more than two hundred leagues, was at the first signal to turn round and march on the Danube, in several columns! The order of the marches, their duration, points of concentration, of reunion of the columns, surprises, attacks, various movements, the enemy's mistakes—all was foreseen.... The battlefields, the victories, even the dates on which we were to enter Munich and Vienna—all was then written just as it happened, and this two months in advance, at this very hour of the 13th of August, and from this quarter-general on the coast. Daru, however accustomed to the inspirations of his chief, remained dumfounded, and he was even more surprised when afterwards he saw these oracles realized. The Emperor returned to Paris without delay, and there laid before the Senate the state of the army and announced the commencement of hostilities.
It was five years since the soldiers had been in battle; and for two and a half years they had been waiting in vain for an opportunity to cross over into England. It would be difficult to form any conception then of their joy or of their ardor when they learned they were going to be employed in a great war. Old and young ardently longed for battles, dangers, distant expeditions. They had conquered the Austrians, the Prussians, the Russians; they despised all the soldiers of Europe and did not imagine there was an army in the world capable of resisting them. They set off singing, and shouting, "Vive l'Empereur!"
At the same time Massena received orders to assume the offensive in Italy, and force his way, if possible, into the hereditary States of Austria. The two French armies, one crossing the Rhine and the other pushing through the Tyrolese, looked forward to a junction before the walls of Vienna. After appointing Joseph Bonaparte to superintend the government in his absence Napoleon quitted Paris on the 24th of September 1805, accompanied as far as Strasbourg by Josephine: here they separated. The Emperor put himself at the head of his army and crossed the Rhine on the 1st of October. He now begun a series of grand manoeuvres and partial actions, requiring consummate skill, with a view to the destruction of the great Austrian army under General Mack.
Mack, at the head of the Austrian forces, established his headquarters on the western frontier of Bavaria, at Ulm. Prudence would have suggested that he occupy the line of the river Inn, which, extending from the Tyrol to the Danube at Passau, affords a strong defense to the Austrian territory, and on which he might have awaited, in comparative safety, the arrival of the Russian forces, then on the march to aid Austria in the campaign.
Napoleon hastened to profit by Mack's error, and by a combination of manoeuvres with his different divisions, the great body of the French army advanced into the heart of Germany by the left of the Danube, and then throwing himself across the river, took ground in the Austrian general's rear, when he expected to be assaulted in front of Ulm. As it was, Mack's communication with Vienna was interrupted, and he was completely isolated.