War of the Third Coalition

In March 1802, France and Britain agreed to cease hostilities under the Treaty of Amiens. For the first time in ten years, all of Europe was at peace. However, many problems persisted between the two sides making the implementation of the treaty increasingly difficult. Bonaparte was angry that British troops had not evacuated the island of Malta. The tension only worsened when Bonaparte sent an expeditionary force to re-establish control over Haiti. Prolonged intransigence on these issues led Britain to declare war on France on 18 May 1803 despite the fact that Bonaparte finally accepted the occupation of Malta by the British. The nascent Third Coalition came into being in December 1804 when, in exchange for payment, an Anglo-Swedish agreement was signed allowing the British to use Swedish Pomerania as a military base against France.

Napoleon's planned invasion of the United Kingdom at the start of the War of the Third Coalition, although never carried out, was a major influence on British naval strategy and the fortification of the coast of southeast England. French attempts to invade Ireland in order to destabilise the United Kingdom or as a stepping-stone to Great Britain had already occurred in 1796. From 1803 to 1805 a new army of 200,000 men, known as the Armée des côtes de l'Océan was gathered and trained at camps at Boulogne, Bruges and Montreuil. A large "National Flotilla" of invasion barges was built in Channel ports along the coasts of France and the Netherlands right from Étaples to Flushing, and gathered at Boulogne. These preparations were financed by the Louisiana Purchase of 1803, whereby France ceded her huge North American territories to the United States in return for a payment of 50 million French francs ($11,250,000). The entire amount was spent on the projected invasion.

The Grande Armée was formed in 1804 from the L'Armée des côtes de l'Océan (Army of the Ocean Coasts), a force of over 100,000 men that Napoleon had assembled for the proposed invasion of Britain. Napoleon later deployed the army in eastern Europe to eliminate the combined threat of Austria and Russia, which were part of the Third Coalition assembled against France. Thereafter, the name Grande Armée was used for the principal French Army deployed in the campaigns of 1805 and 1807, where it earned its prestige, and in 1812, 1813–14, and 1815. In practice, however, the term Grande Armée is used in English to refer to all the multinational forces gathered by Napoleon in his campaigns.

Upon its formation, the Grande Armée consisted of six corps under the command of Napoleon's marshals and senior generals. When the Austrian and Russian armies began preparations to invade France in late 1805, the Grande Armée was quickly ordered across the Rhine into southern Germany, leading to Napoleon's victories at Ulm and Austerlitz. The French army grew as Napoleon seized power across Europe, recruiting troops from occupied and allied nations; it reached its peak of one million men at the start of the Russian campaign in 1812, with the Grande Armée reaching its height of 413,000 French soldiers, who would take part in the invasion, with the total invasion force exceeding 600,000 men when including foreign recruits.

In addition to its size and multinational composition, the Grande Armée was known for its innovative formations, tactics, logistics, and communications. Unlike most armed forces at the time, it operated on a strictly meritocratic basis; while most contingents were commanded by French generals, except for the Polish and Austrian corps, most soldiers could climb the ranks regardless of class, wealth, or national origin.

Elements of the Royal Navy conducted a naval assault on the fortified French port of Boulogne, during the Napoleonic Wars. It differed from the conventional tactics of naval assaults of the period by utilizing a wide range of new equipment produced by the American-born inventor Robert Fulton, with the backing of the Admiralty. Despite its ambitious aims the assault produced little material damage to the French fleet anchored in the harbour, but did perhaps contribute to a growing sense of defeatism amongst the French as to their chances of crossing the English Channel in the face of the Royal Navy and launching a successful invasion of the United Kingdom.

In December 1804, an Anglo-Swedish agreement led to the creation of the Third Coalition. British Prime Minister William Pitt the Younger spent 1804 and 1805 in a flurry of diplomatic activity to form a new coalition against France. Mutual suspicion between the British and the Russians eased in the face of several French political mistakes, and by April 1805, the first two had signed a treaty of alliance. Having been defeated twice in recent memory by France and keen on revenge, Austria also joined the coalition a few months later. The stated goal of the Anglo-Russian alliance was to reduce France to its 1792 borders. Austria, Sweden, and Naples would eventually join this alliance, whilst Prussia again remained neutral.

Fought at Ulm-Jungingen north of Ulm at the Danube between French and Austrian forces. The effects of the Battle of Haslach-Jungingen on Napoleon's plans are not fully clear, but the Emperor may have finally ascertained that the majority of the Austrian army was concentrated at Ulm.

Only the corps of Michael von Kienmayer and Franz Jellacic escaped envelopment by the Grande Armée of Napoleon. As Kienmayer's columns fled to the east, they joined with elements of the Russian Empire's army in a rear guard action at the Battle of Amstetten on 5 November. A few days later, Davout's III Corps caught up with Merveldt's division at Mariazell. The Austrian soldiers, their morale shaken by continuous retreating, were routed after a brief struggle.

The Confederated States of the Rhine, simply known as the Confederation of the Rhine, also known as Napoleonic Germany, was a confederation of German client states established at the behest of Napoleon some months after he defeated Austria and Russia at the Battle of Austerlitz. Its creation brought about the dissolution of the Holy Roman Empire shortly afterward. The Confederation of the Rhine lasted from 1806 to 1813.

The founding members of the confederation were German princes of the Holy Roman Empire. They were later joined by 19 others, altogether ruling a total of over 15 million subjects. This granted a significant strategic advantage to the French Empire on its eastern frontier by providing a buffer between France and the two largest German states, Prussia and Austria (which also controlled substantial non-German lands).

Key Findings:

• The Napoleonic Kingdom of Italy gains Venice, Istria, Dalmatia from Austria
• Bavaria gains Tyrol
• Württemberg gains Habsburg territories in Swabia
• Napoleon establishes the Kingdom of Holland and the Grand Duchy of Berg
• The Holy Roman Empire dissolves, Franz II adbicates his title of Holy Roman Emperor
• The Confederation of the Rhine forms from German princes of the former Holy Roman Empire.