Editing War of the Third Coalition (section)

== Periodisation ==
Historians 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, not until 11 April 1805 when Russia joined the alliance, not until 16 July when Britain and Russia ratified their treaty of alliance, and only thereafter Austria (9 August) and Naples–Sicily (11 September) completed the fully-fledged coalition.

Meanwhile, [[Electorate of Bavaria|Bavaria]] sided with France on 25 August following the [[Treaty of Bogenhausen]], and [[Electorate of Württemberg|Württemberg]] joined Napoleon on 5 September. No major hostilities between France and any member of the coalition other than Britain ([[Trafalgar campaign]] March–November 1805) occurred until the [[Ulm Campaign]] (25 September – 20 October 1805). This was in part because [[Napoleon's planned invasion of the United Kingdom]] was not called off until 27 August 1805, when he decided to use his invasion force [[Camp of Boulogne|camped at Boulogne]] against Austria instead.

Likewise, no major battles occurred after the Battle of Austerlitz and the signing of the [[Peace of Pressburg (1805)|Peace of Pressburg]] on 26 December 1805, which forced Austria to leave the Third Coalition and cease hostilities against France. Some historians conclude that Austria's departure "shattered the fragile Third Coalition" and "ended the War of the Third Coalition".{{sfn|Rosenberg| 2017|p=168}}

This narrative leaves out the subsequent [[Invasion of Naples (1806)|French invasion of Naples]] (February–July 1806), which the [[Anglo-Russian occupation of Naples|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.{{sfn|Pagedas|2005|pp=120–122}}