War of the III Coalition · 1805–1806
By the summer of 1805, Napoleon had some 180,000 men of the Army of the Coasts of the Ocean at Boulogne on the Channel — the camp there was preparing to invade England. On 11 April Russia and Great Britain signed the Treaty of Saint Petersburg — prepared by Czartoryski; on 8 August Austria acceded — forming the Third Coalition. On France’s side stood allied Spain under Godoy: its fleet under Gravina was tied to Villeneuve’s squadron.
Marshals of the campaign
12 marshals
Key events
- 1805Politics
By summer, the Army of the Coasts of the Ocean — some 180,000 men under Napoleon — is encamped at Boulogne on the Channel coast, poised to invade England.
- 11 AprTreaty
Russia and Great Britain sign the Treaty of Saint Petersburg — the foundation of the Third Coalition against France.
- 8 AugPolitics
Austria accedes to the Treaty of Saint Petersburg; the Third Coalition is fully formed.
- 20 SepPolitics
Breaking camp at Boulogne, the Grande Armée crosses the Rhine and opens the autumn campaign — a grand march toward the Danube. Meanwhile, Masséna commands the army in Italy.
- 20 OctBattle
At Ulm, Mack's Austrian army is surrounded and surrenders — about 27,000 prisoners, without a major pitched battle.
- 21 OctBattle
Off Cape Trafalgar Nelson and Collingwood crush the Franco-Spanish fleet of Villeneuve and Gravina; Churruca falls aboard the *San Juan Nepomuceno*. Allied Spain shares France’s fate at sea. Britain keeps command of the sea, but the outcome on land is unchanged.
- 29 OctBattle
At Caldiero in Italy, Masséna holds Archduke Charles. The Italian front is secured, though the decisive battle came on another front.
- 5 Nov
- 11 Nov
- 13 NovPolitics
The French enter Vienna. Emperor Francis II withdraws north toward the Russian columns.
- 16 NovBattle
At Schöngrabern (Hollabrunn) Bagration's rearguard checks the pursuit — the Grande Armée is delayed a day before Austerlitz.
- 2 DecBattle
The Battle of the Three Emperors at Austerlitz: Soult's corps seizes the Pratzen Heights and the allied army is defeated.
- 26 DecTreaty
Treaty of Pressburg: Austria leaves the war, loses influence in Germany, and cedes territory in Italy.
- 1806Politics
Francis II renounces the title of Holy Roman Emperor — the political aftermath of the Third Coalition's defeat.
Sides and key participants
Campaign results
For France
- Victory at Austerlitz and Austria's exit from the war
- Treaty of Pressburg — stronger position in Franconia and northern Italy
- Creation of the Confederation of the Rhine and weakening of the Habsburgs
- Destruction of the Franco-Spanish fleet at Trafalgar while dominance on land holds
- Prelude to the end of the Holy Roman Empire (1806)
For the coalition
- Destruction of the Austrian field army and loss of a continental ally
- Russian withdrawal — land war deferred until 1806–1807
- Britain remains at sea; Trafalgar (1805) does not change the outcome on land
- The Third Coalition collapsed