The war at sea culminated in the Battle of Trafalgar, on October 21, 1805. On September 14, Napoleon had instructed Adm. Pierre-Charles-Jean-Baptiste-Silvestre de Villeneuve at Cádiz to enter the Mediterranean and to hold some of the coalition’s forces in Italy by attacking Naples while the French army marched to the Danube. On October 19–20, Villeneuve left harbour with 33 ships of the line, his Spanish vessels mingled with the French. Nelson met him off Cape Trafalgar with 27 ships. The French and Spanish lost 19 ships on the day of the battle, and 4 more were captured early in November; the British lost none in the battle or in the storm which followed. Nelson and 448 British were killed and an additional 1,200 were wounded. French and Spanish casualties numbered about 4,400 killed, 2,500 wounded, and 7,000 captured, including Villeneuve. The immediate result was to frustrate French plans for a diversion against Naples, and there could be no return to plans for an invasion of England.

The Anglo-Russian force that landed at Naples in November 1805 arrived long after Napoleon had withdrawn his troops from the south to strengthen his defenses on the Mincio and too late to affect the outcome of the year’s campaigns. The Neapolitans welcomed it and joined the coalition, but the French forced the allies to withdraw to Corfu and Sicily (Reggio, on the mainland, remained in British hands until February 17, 1808). Napoleon’s brother Joseph was proclaimed king of Naples on March 30, 1806, in place of the Bourbon Ferdinand IV (whose deposition Napoleon had announced in December 1805). With the occupation of the Papal States the whole of Italy was under French control.

Hanover and the Confederation of the Rhine

In Vienna on December 15, 1805, Napoleon and Haugwitz drafted the Treaty of Schönbrunn whereby Prussia was to enter into an offensive-defensive alliance with France; cede Neuchâtel, Cleves, and Ansbach; and acquire Hanover. The Prussian government, wishing simply to occupy Hanover until peace should have been made, did not ratify this treaty. However, it was soon forced, under the Treaty of Paris (February 15, 1806), to annex Hanover outright and to close the Prussian as well as the Hanoverian ports to British commerce. Great Britain consequently declared war on Prussia (April 21) and seized 250 Prussian ships in British harbours.

Having thus embroiled Prussia with Great Britain, Napoleon obstructed the plan for a confederation, under Prussian leadership, to include Saxony and other states of northern Germany. He set up his brother Louis as king of Holland (June 1806) and then proceeded to form the Confederation of the Rhine in July, embracing Bavaria, Württemberg, Baden, Aschaffenburg, Hesse-Darmstadt, Nassau, Berg, and several smaller states of western Germany, with himself as its protector. When these confederates announced that the ancient Reich had ceased to exist, Francis of Austria acquiesced by renouncing his title of Holy Roman emperor (August 1806). Negotiations had meanwhile been proceeding between the belligerents, but Charles James Fox’s ministry, which had taken office in Great Britain after Pitt’s death (January 1806), made no more progress with Napoleon than did the Russians.

The Russo-Prussian alliance

The hardening of anti-French feeling in Berlin put an end to an uneasy stalemate, and Russia and Prussia signed a secret defensive alliance against France in July 1806. Napoleon, however, still discounted the notion that Prussia might go to war against him. He was preparing to honour his undertaking to withdraw French forces from Germany even when Prussia, on August 9, had ordered partial mobilization. Growing tension in Prussia and the stronger tone of Russian diplomacy soon made him change his mind. On September 5, 1806, a day before the Prussians opened the North Sea ports to the British, he instructed his forces in the triangle of Coblenz, Constance, and Passau to regroup farther north between Frankfurt and Amberg.

Prussia had chosen to go to war with France in far less favourable circumstances than those which had existed in 1805. The French were now within easy reach of the frontier, the Austrians could no longer intervene, and the Russians were behind the Vistula. Furthermore, the Prussian army had little light infantry, poor artillery and only cumbersome supply trains and had not yet adopted the divisional system. In the face of Napoleon’s army corps, the Prussians took the field in three armies commanded by elderly men. The first and fundamental mistake of the Prussian high command was to come forward, instead of withdrawing to form a line along the Elbe and awaiting the arrival of the Russians.

The campaign of Jena and Auerstädt

Having won the support of the elector Frederick Augustus of Saxony, the Prussians marched into Saxon territory on September 13, 1806. The news reached Paris five days later, and on September 19 Napoleon ordered the concentration of the Grande Armée, by the beginning of October, along the Main as far as Bamberg and thence to the south. At Mainz on September 29 he learned that the Prussians were still between Eisenach and Hildburghausen in front of the Thuringerwald and roughly at right angles with the Main. This news suggested that Napoleon had time to enter Saxony so as to appear in the rear of their left flank. Having reached Würzburg on October 2, he closed up his forces, and on October 5 he gave orders for the march to the northeast. In three columns, the French were to cross the Frankenwald and debouch on the upper Saale at Saalfeld, Schleiz, and Hof. On October 9 a Saxon division was attacked at Schleiz. The following day a Prussian detachment was routed at Saalfeld, and Hof was occupied without opposition. While Napoleon continued his advance toward Gera, the Prussian army under Prince Friedrich von Hohenlohe retired northward to Kahla, 20 miles (32 km) to the west of Napoleon’s objective.

The engagement of Saalfeld convinced the Prussians that they might be cut off from the Elbe, and they decided to concentrate their forces, under King Frederick William III and Charles William Ferdinand of Brunswick, at Weimar. When the French forces reached the Saale (October 12, 1806), Napoleon ceased his march to the northeast and moved his forces to the left to close in on the river line. As Hohenlohe retreated from Kahla to Jena, Napoleon swung his right wing northwestward to gain the Saale and march up its right bank, while the main body of the French was directed to cross the river between Kahla and Jena and then to advance on the mass of the Prussian forces. By the evening of October 12 Napoleon’s main advance guard had made contact with the outposts left at Jena by Hohenlohe. Louis-Nicolas Davout, commanding the French Third Corps, was at Naumburg, 20 miles (32 km) downstream, within easy reach of the roads from Weimar along the left bank of the Saale via Auerstädt and Freiburg toward the Elbe. The following day, the French routed the Prussians at the battles of Jena and Auerstädt. Napoleon swept Hohenlohe’s forces from the field at Jena, while a vastly outnumbered Davout destroyed the main Prussian army under Charles William Ferdinand at Auerstädt. The Prussians lost 22,000 killed and wounded in the two battles and 18,000 prisoners. Among those lost was Charles William Ferdinand, who succumbed to his wounds on November 10. The most famous pursuit of the Napoleonic period began on October 15 and ended with the capitulation, at Ratkau, near Lübeck, on November 7, of Gebhard Leberecht von Blücher’s detachment. Of the Prussian army, only 15,000 men under Anton Wilhelm von Lestocq escaped to East Prussia. Together with 120,000 prisoners, vast quantities of matériel had been taken: one month’s campaigning had destroyed the Prussian war machine.

The price of such defeat was severe. Pending the final settlement a war contribution of 160,000,000 francs and extensive requisitions throughout northern Germany were exacted. Napoleon’s immediate demands were for all Prussian territory west of the Elbe except Magdeburg and the Altmark, but the rapid collapse of Prussia, the Russian advance into Prussian Poland (October 23, 1806), and the disclosure of the Russo-Prussian alliance soon led him to offer an armistice instead of a peace treaty. On November 10 he announced that he would occupy Berlin until a general settlement had been made, including the restoration by the British of the colonies seized from the French and their allies. Frederick William preferred to remain in the allied camp. Meanwhile the French had occupied Brunswick and Hesse-Kassel, and Würzburg had joined the Confederation of the Rhine in September. The peace of Posen (Poznań) between France and Saxony was concluded on December 11, 1806, bringing Saxony into the Confederation of the Rhine and giving its elector, Frederick Augustus, the title of king.