The Fourth Coalition against Napoleon's French Empire was defeated in a war spanning 1806–1807. Coalition partners included Prussia, Russia, Saxony, Sweden, and the United Kingdom.

Many members of the coalition had previously been fighting France as part of the Third Coalition, and there was no intervening period of peace. In 1806, Prussia joined the coalition fearing the rise in French power after the defeat of Austria and establishment of the French-backed Confederation of the Rhine. Prussia and Russia mobilized for a fresh campaign, and Prussian troops massed in Saxony.

Overview

Napoleon decisively defeated the Prussians in a lighting campaign that culminated at the Battle of Jena-Auerstedt on 14 October 1806. French forces under Napoleon occupied Prussia, pursuing the remnants of the shattered Prussian Army, and captured Berlin on October 25 1806, then moved all the way to East Prussia, Poland and the Russian frontier, where they fought an inconclusive battle against the Russians at Eylau in February 1807. Napoleon's advance on the Russian frontier was briefly checked. Russian forces were crushed by Napoleon's army at Friedland on June 14, 1807, and three days later Russia asked for a truce. By the Treaties of Tilsit in July 1807, France made peace with Russia and received half of Prussia's territory, Jerome Bonaparte's Kingdom of Westphalia, and the new Duchy of Warsaw. Napoleon was now master of all of western and central continental Europe, except for Spain, Portugal, Austria and several smaller countries.

Origins

The Fourth Coalition (1806–1807) of Prussia, Russia, Saxony, Sweden and the United Kingdom against France formed within months of the collapse of the previous coalition. Following his triumph at the Battle of Austerlitz and the subsequent demise of the Third Coalition, Napoleon looked forward to achieving a general peace in Europe, especially with his two main remaining antagonists, Britain and Russia. Meanwhile, he sought to isolate Prussia from the influence of these two powers by offering a tentative alliance, while at the same time seeking to curb Prussia's political and military influence among the German states.

Despite the death of William Pitt in January 1806, Britain and the new Whig administration remained committed to checking the growing power of France. Peace overtures between the two nations early in the new year proved intransigent (with one point of negotiations, the fate of Hanover, becoming a casus belli for both Britain and Prussia against France). The main conflict between Britain and France for the coming war would involve an escalation in economic warfare between the two powers. With Britain still retaining her dominance of the seas, Napoleon looked to break this dominance with his issuance of the Berlin Decree and the beginnings of his Continental System . Britain retaliated with its Orders in Council several months later.

In the mean time, Russia was still licking her wounds from the previous year's campaign. Napoleon had hoped to establish peace with Russia and a tentative peace treaty was signed in July, 1806, but this was vetoed by Tsar Alexander I and the two powers remained at war. Though nominally an ally in the coalition, Russia remained a dormant entity for much of the year (giving virtually no military aid to Prussia in the main battles that October as Russian armies were stil mobilising). Russian forces would not fully come into play in the war until late 1806 when Napoleon entered Poland.

Finally, Prussia had remained at peace with France the previous year, though it did come close to joining the Allies when a French corps led by Marshal Bernadotte illegally violated the neutrality of Ansbach on their march to face the Austrians and Russians. Anger by Prussia at this trespass was tempered by the results of Austerlitz, and a convention of continued peace with France was signed two weeks after that battle at Schönbrunn. This convention was modified two months later, with one clause in effect promising to give Hannover to Prussia in exchange for Ansbach going over to France's ally, Bavaria. Relations between France and Prussia however, quickly soured when it was revealed that Napoleon had also secretly promised to return sovereignty of Hannover back to Britain during his abortive negotiations with the British. This duplicity by the French would be one of the main causes for Prussia declaring war that autumn. Another cause was Napoleon's formation in July 1806 of the Confederation of the Rhine out of the many tiny German states which constituted the Rhineland and most other parts of western Germany. A virtual satellite of the French Empire, the Confederation was intended to act as a buffer state from any future aggressions from Austria, Russia or Prussia. Napoleon amalgamated many of the smaller states into larger electorates, duchies and kingdoms to make the governance of non-Prussian Germany more efficient. Napoleon elevated the rulers of the two largest Confederation states, his allies Württemberg and Bavaria, to the status of kings. Understandably, Prussia was indignant at this meddling in the affairs of German homogeneity (without its involvement or even consultation) and viewed it as a threat. After giving Napoleon an ultimatum on October 1, 1806, Prussia (supported by Saxony) finally decided to contend militarily with the French Emperor.

Prussian campaign

In August 1806, the Prussian king, Friedrich Wilhelm III made the decision to go to war independently of any other great power, save the distant Russia. Another course of action might have involved declaring war the previous year and joining Austria and Russia. This might have contained Napoleon and prevented the Allied disaster at Austerlitz. In any event, the Russian army, an ally of Prussia, still remained far away when Prussia declared war. In September, Napoleon unleashed all French forces east of the Rhine, deploying the corps of his Grande Armée in southern Saxony. After Lannes defeated a Prussian detachment at Saalfeld, four days later Napoleon himself defeated a Prussian army at Jena (October 14 1806), and Davout defeated another at Auerstädt on the same day. Some 160,000 French soldiers (increasing in number as the campaign went on) went against Prussia and moved with such speed that Napoleon was able to destroy as an effective military force the entire quarter of a million strong Prussian army — which sustained 25,000 casualties, lost a further 150,000 prisoners and 4,000 artillery pieces, and over 100,000 muskets stockpiled in Berlin. In the former battle, Napoleon only fought a detachment of the Prussian force. The latter battle involved a single French corps under Marshal Davout defeating the bulk of the Prussian army (for this he was later created the Duke of Auerstädt). Napoleon entered Berlin on 27 October 1806 and visited the tomb of Frederick the Great, there instructing his marshals to remove their hats, saying, In total, Napoleon had taken only 19 days from beginning his attack on Prussia until knocking it out of the war with the capture of Berlin and the destruction of its principal armies at Jena and Auerstadt. Saxony was elevated to a kingdom on 11 December, 1806 upon joining the Confederation of the Rhine and leaving the Allied Coalition.

In Berlin, Napoleon issued a series of decrees which, on November 21, 1806 brought into effect the Continental System. This policy aimed to eliminate the threat of the United Kingdom by closing French-controlled territory to its trade.

Polish and Russian campaigns

The French entered Poland and Napoleon Bonaparte created a new Duchy of Warsaw, to be ruled by the new King of Saxony. The area of the duchy had already been liberated by a popular uprising that had escalated from anti-conscription rioting. Napoleon then turned north to confront the remainder of the Russian army and to attempt to capture the temporary Prussian capital at Königsberg. A tactical draw at Eylau (February 7–8) forced the Russians to withdraw further north. Napoleon then routed the Russian army at Friedland (June 14). Following this defeat, Alexander had to make peace with Napoleon at Tilsit (July 7, 1807). By September, Marshal Brune completed the occupation of Swedish Pomerania, allowing the Swedish army, however, to withdraw with all its munitions of war.

Results

At the Congress of Erfurt (September–October 1808) Napoleon and Alexander agreed that Russia should force Sweden to join the Continental System, which led to the Finnish War of 1808–1809 and to the division of Sweden into two parts separated by the Gulf of Bothnia. The eastern part became the Russian Grand Duchy of Finland. Due to the Continental System, the United Kingdom was yet again still at war with Napoleon and was not affected by the peace treaty.