War of the Third Coalition

War of the Third Coalition
Part of the Napoleonic Wars and the Coalition Wars
Napoléon at the Battle of Austerlitz, by François Pascal Simon, Baron Gérard
Date18 May 1803 – 18 July 1806

French victory


Third Coalition:
 Holy Roman Empire

 Austrian Empire
 United Kingdom


French satellites:

Commanders and leaders
Holy Roman Empire Francis II
Holy Roman Empire Karl Mack von Leiberich
Holy Roman Empire Archduke Charles
Russian Empire Alexander I
Russian Empire Mikhail Kutuzov
British Empire Henry Addington
British Empire William Pitt the Younger
British Empire Lord Grenville
British Empire Viscount Nelson 
Kingdom of Naples Ferdinand IV
First French Empire Napoleon I
First French Empire André Masséna
First French Empire Pierre-Charles Villeneuve
First French Empire Michel Ney
First French Empire Louis-Nicolas Davout
First French Empire Pierre Augereau
First French Empire Jean-Baptiste Bernadotte
First French Empire Jean Lannes
First French Empire Joachim Murat
First French Empire Jean-de-Dieu Soult
First French Empire Auguste Marmont
First French Empire Édouard Mortier
Spain Charles IV
Spain Federico Gravina
Kingdom of Italy (Napoleonic) Charles Louis
Kingdom of Italy (Napoleonic) Eugène de Beauharnais
Casualties and losses


Holy Roman Empire 90,000[1]
  • 20,000 killed and wounded
  • 70,000 captured

Russian Empire 50,000[1]

  • 25,000 killed and wounded
  • 25,000 captured
Kingdom of Naples 20,000


First French Empire 55,500
  • 13,500 killed
  • 37,000 wounded
  • 5,000 captured

Spain 2,800

  • 1,200 killed
  • 1,600 wounded

Kingdom of Italy (Napoleonic) 2,250

  • 350 killed
  • 1,900 wounded

Electorate of Bavaria 1,500

  • 300 killed
  • 1,200 wounded

The War of the Third Coalition[note 1] was a European conflict spanning the years 1803 to 1806. During the war, France and its client states under Napoleon I defeated an alliance, the Third Coalition, made up of the Holy Roman Empire (actually Austria), Russia, Britain and others. Prussia remained neutral during the war.

Britain had already been at war with France following the resumption of hostilities resulting from the breakdown of the Peace of Amiens and remained the only country still at war with France after the Treaty of Pressburg. From 1803–05, Britain stood under constant threat of a French invasion. The Royal Navy, however, secured mastery of the seas and decisively destroyed a Franco-Spanish fleet at the Battle of Trafalgar in October 1805.

The Third Coalition itself came to full fruition in 1804–05 as Napoleon's actions in Italy (crowning himself with the Iron Crown of Lombardy) and Germany (notably the arrest and execution of the Duc d'Enghien) spurred Austria and Russia into joining Britain against France. The war would be determined on the continent, and the major land operations that sealed the swift French victory involved the Ulm Campaign, a large wheeling manoeuvre by the Grande Armée lasting from late August to mid-October 1805 that captured an entire Austrian army, and the decisive French victory over a combined Russo-Austrian force under Tsar Alexander I at the Battle of Austerlitz in early December. Austerlitz effectively brought the Third Coalition to an end, although later there was a small side campaign against Naples, which also resulted in a decisive French victory at the Battle of Campo Tenese.

On 26 December 1805, Austria and France signed the Treaty of Pressburg, which took Austria out of both the war and the Coalition, while it reinforced the earlier treaties between the two powers of Campo Formio and of Lunéville. The treaty confirmed the Austrian cession of lands in Italy and Bavaria to France and in Germany to Napoleon's German allies, imposed an indemnity of 40 million francs on the defeated Habsburgs, and allowed the defeated Russian troops free passage, with their arms and equipment, through hostile territories and back to their home soil. Victory at Austerlitz also permitted the creation of the Confederation of the Rhine, a collection of German states intended as a buffer zone between France and central Europe. As a direct consequence of these events, the Holy Roman Empire ceased to exist when, in 1806, Holy Roman Emperor Francis II abdicated the Imperial throne, emerging as Francis I, Emperor of Austria. These achievements, however, did not establish a lasting peace on the continent. Austerlitz had driven neither Russia nor Britain, whose armies protected Sicily from a French invasion, to settle. Meanwhile, Prussian worries about growing French influence in Central Europe sparked the War of the Fourth Coalition in 1806.


Historiographers differ on when the War of the Third Coalition began and when it ended. From the British perspective, the war started when Britain declared war on France on 18 May 1803, but it was still on its own. It was not until December 1804 when Sweden entered into an alliance with the United Kingdom, until 11 April 1805 when Russia joined the alliance and only thereafter Austria and Naples–Sicily completed the fully-fledged coalition. No major hostilities between France and any member of the coalition other than Britain occurred until the September 1805 Ulm Campaign. Likewise, no major battles occurred after the Battle of Austerlitz and the signing of the Peace of Pressburg on 26 December 1805, which forced Austria to leave the Third Coalition and cease hostilities against France. Some historiographers conclude that Austria's departure "shattered the fragile Third Coalition"[3] and "ended the War of the Third Coalition".[4] This narrative leaves out the subsequent French invasion of Naples (February–July 1806), which the occupying Anglo-Russian troops hastily evacuated and the remaining Neapolitan forces relatively quickly surrendered. Other scholars argue the southern Italian campaign should be included into the War of the Second Coalition, and criticise ignoring the Mediterranean front by only focusing on land battles in Central Europe and the Trafalgar Campaign.[5]