The Third Coalition itself came to full fruition in 1804–05 as Napoleon's actions in Italy and Germany (notably the arrest and execution of the Duc d'Enghien) spurred Austria and Russia into joining Britain against France.

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.

[1] 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.

[11] In August 1805, Napoleon, Emperor of the French since May of the previous year, turned his army's sights from the English Channel to the Rhine in order to deal with the new Austrian and Russian threats.

The War of the Third Coalition began with the Ulm Campaign, a series of French and Bavarian military manoeuvres and battles designed to outflank an Austrian army under General Mack.

General Mack thought that Austrian security relied on sealing off the gaps through the mountainous Black Forest area in Southern Germany that had witnessed much fighting during the campaigns of the French Revolutionary Wars.

Mack decided to make the city of Ulm the centrepiece of his defensive strategy, which called for containment of the French until the Russians under Mikhail Kutuzov could arrive and alter the odds against Napoleon.

Napoleon had other intentions: 210,000 French troops would be launched eastwards from the camps of Boulogne and would envelop General Mack's exposed Austrian army if it kept marching towards the Black Forest.

The left-wing of the Grande Armée would move from Hanover and Utrecht to fall on Württemberg; the right and centre, troops from the Channel coast, would concentrate along the Middle Rhine around cities like Mannheim and Strasbourg.

While Murat was making demonstrations across the Black Forest, other French forces would then invade the German heartland and swing towards the southeast by capturing Augsburg, a move that was supposed to isolate Mack and interrupt the Austrian lines of communication.

Napoleon did not seriously consider the possibility that Mack would cross the Danube and move away from his central base, but he did realize that seizing the bridges at Günzburg would yield a large strategic advantage.

For reasons not entirely clear, Mack ordered Auffenburg on 7 October to take his division of 5,000 infantry and 400 cavalry from Günzburg to Wertingen in preparation for the main Austrian advance out of Ulm.

The French were separated in two massive rings at this point: the forces of Ney, Lannes and Murat to the west were containing Mack, while those of Soult, Davout, Bernadotte and Marmont to the east were charged with guarding against any possible Russian and Austrian incursions.

The Austrians flooded the battle with more cavalry and infantry regiments to Jungingen hoping to score a knockout blow against Ney's corps by enveloping Dupont's force.

Ferdinand began to openly oppose Mack's command style and decisions, charging that the latter spent his days writing contradictory orders that left the Austrian army marching back and forth.

[20] As part of Napoleon's plans to invade the United Kingdom, the French and Spanish fleets combined to take control of the English Channel and provide the Grande Armée safe passage.

They encountered the British fleet under Lord Nelson, recently assembled to meet this threat, in the Atlantic Ocean along the southwest coast of Spain, off Cape Trafalgar.

This was a trap on the part of Kutuzov, laid for the sole purpose of convincing Mortier that he had retreated further toward Vienna, when he had actually crossed the Danube in force, and lay concealed behind the ridges above the village.

[30] On 28 November, Napoleon met with his marshals at Imperial Headquarters and they informed him of their qualms and fears about the upcoming battle, even suggesting a retreat, but he shrugged off their complaints and went to work.

This sector of the battlefield witnessed heavy action in the following moments as several ferocious Allied charges evicted the French from the town and forced them on the other side of the Goldbach.

[32] Around 8:45 a.m., finally satisfied at the weakness in the enemy centre, Napoleon asked Soult how long it would take for his men to reach the Pratzen Heights, to which the Marshal replied, "Less than twenty minutes, sire."

"[33] A dense fog helped to cloud the advance of St. Hilaire's division, but as they went up the slope the legendary 'Sun of Austerlitz' ripped the mist apart and encouraged them forward.Russian soldiers and commanders on top of the heights were stunned to see so many French troops coming towards them.

To the north, General Vandamme's division attacked an area called Staré Vinohrady and through talented skirmishing and deadly volleys broke several Allied battalions.

Napoleon ordered Bernadotte's I Corps to support Vandamme's left and moved his own command centre from Zuran Hill to St. Anthony's Chapel on the Pratzen Heights.

The Russians had a numerical advantage here but fairly soon the tide swung as d'Erlon's Division, the 2nd of Bernadotte's I Corps, deployed on the flank of the action and allowed French cavalry to seek refuge behind their lines.

In an effective double-pronged assault, St. Hilaire's division and part of Davout's III Corps smashed through the enemy at Sokolnitz and persuaded the commanders of the first two columns, generals Kienmayer and Langeron, to flee as fast as they could.

Ferdinand had hoped for a repeat of the events of 1799, when a popular uprising in Calabria eventually caused the downfall of the Parthenopaean Republic, a French client state created after the Neapolitans were defeated the first time during the War of the Second Coalition.

By now, the last regular troops of the Neapolitan army had fled to Sicily and the French controlled the entire Italian mainland except for the fortress of Gaeta, which had been under siege since 26 February.

Austria agreed to recognize French territory captured by the treaties of Campo Formio (1797) and Lunéville (1801), cede land to Bavaria, Württemberg, and Baden, which were Napoleon's German allies, and pay 40 million francs in war indemnities.

With Napoleon as their "Protector", the confederate states were compelled to leave the Holy Roman Empire, which was dissolved shortly afterward.<[40]Prussia saw these and other moves as an affront to its status as the main power of Central Europe and it went to war with France in 1806.