In 1809, Europe was embroiled in warfare, pitting France against a series of coalitions in the Coalition Wars almost continuously since 1792. A brief period of peace followed the March 1802
Treaty of Amiens before Anglo-French relations deteriorated, leading to the
War of the Third Coalition in May 1803. Britain was joined in their coalition by
Sweden in 1804 and Russia and Austria in 1805. In August 1805, the 200,000-strong French
Grande Armée invaded the German states, hoping to defeat Austria before Russian forces could intervene. The French emperor
Napoleon successfully wheeled his army into the Austrian rear and defeated them at the
Battle of Ulm, fought from 15 to 20 October. The
Treaty of Pressburg, signed soon afterwards, ended Austrian participation in the war. Austerlitz incited a major shift in the European balance of power.
Prussia felt threatened in the region and, alongside Russia, declared war against France in the 1806
War of the Fourth Coalition. After French victories at the
Battle of Jena-Auerstadt on 14 October, France
occupied the Prussian capital, Berlin. France invaded Poland in November, where Russian forces were stationed, and occupied
Warsaw. Russian and French armies fought in February 1807 at the violent, indecisive
Battle of Eylau. The action in Poland culminated on 14 June 1807 when the French defeated Russia at the
Battle of Friedland. The resulting
Treaty of Tilsit in July left France as the dominant power in Western Europe, with many client states including the Duchy of Warsaw. This weakened Prussia and allowed Russia to expand into Finland and South-Eastern Europe.
Peninsular War In 1807, France tried to force Portugal to join the
Continental System, a commercial embargo against Britain. When the Portuguese
prince regent, John, refused to join, Napoleon sent General
Junot to
invade Portugal in 1807, resulting in the six year
Peninsular War. The war weakened the French empire's military, particularly after Spanish forces and civilians rebelled against France after Napoleon overthrew the Spanish king. After the French defeat at the
Battle of Bailén, Napoleon took command of the French forces, defeating the Spanish armies before returning to France. In the beginning of 1809, the French
client kingdom of Spain, ruled by Napoleon's brother
Joseph Bonaparte, controlled much of Spain and northern Portugal. British and Portuguese forces under
Arthur Wellesley launched new offensives from Spring 1809. Spanish regular armies including those led by General
Joaquín Blake continued to fight and
guerrilla activity in the countryside made French operations hazardous. A significant French presence, numbering 250,000 in June 1809, remained in the peninsula throughout the War of the Fifth Coalition. The Napoleonic occupation of France's own ally Spain persuaded many in Austria that Napoleon could not be trusted and declaring war was the only way to prevent him from destroying the
Habsburg monarchy. The Spanish guerrillas inspired popular resistance against Napoleon, and the Austrians hoped that French preoccupation in Spain would make it easier to defeat France.
Austria plans for war After Austria was defeated in 1805, the nation spent three years reforming its army. Encouraged by the events in Spain, Austria sought another confrontation with France to avenge their defeats and regain lost territory and power. Austria lacked allies in central Europe; Russia, its main ally in 1805, made peace with Napoleon at Tilsit and was engaged in wars with erstwhile allies like Britain in the
Anglo-Russian War (1807–12), Sweden in the
Finnish War and the Ottoman Empire in the
Russo-Turkish War (1806–1812). France tried to reinforce their relationship with Russia through the September–October 1808
Congress of Erfurt. Under the treaty Russia agreed to support France if it was attacked by Austria. In early 1809, Austrian minister
Johann Philipp Stadion secured Russian tsar Alexander I's agreement that the Russians would move slowly and "avoid every collision and every act of hostility" during any advance into Austria. At the same time, the French minister
Charles Maurice de Talleyrand-Périgord secretly advised Alexander to resist France. During the War of the Fifth Coalition, Russia remained neutral even though they were allied to France. Austria hoped Prussia would assist them in a war with France but a letter from Prussian minister
Baron von Stein discussing the negotiations was intercepted by French agents and published in the
Le Moniteur Universel on 8 September. Napoleon confiscated Stein's holdings in Westphalia and pressured King
Frederick William III into dismissing him, and Stein fled into exile in Austria. On the same day that Stein was compromised the Convention of Paris agreed a timetable for the withdrawal of foreign troops from Prussia, where French garrisons had been in place since the end of the War of the Fourth Coalition. The withdrawal was contingent on the payment of heavy reparations, totalling 140 million francs, over 30 months. The
Prussian Army was also limited in size to 42,000 men, one sixth of its pre-war total. The convention severely restricted the ability of the Prussian state to wage war. Despite this setback Stadion hoped Prussia would change their mind and that an Austrian advance into the French-controlled
Confederation of the Rhine in Germany would lead to popular uprisings that would distract the French. France withdrew 108,000 troops from Germany, more than half their strength there, to reinforce the French armies in Spain in October 1808. This lent support to Stadion's pro-war faction at the Austrian court. Stadion recalled
Klemens von Metternich, his ambassador to Paris, to convince others to support his plan and by December 1808 Emperor
Francis I was persuaded to support the war. Francis' support was tentative and the decision to proceed was made at an 8 February 1809 meeting that included the emperor,
Archduke Charles and Stadion. The empire's poor financial situation (it could only afford to maintain its army on home soil until late spring) lent urgency to the decision. Charles disputed the prospects for success but accepted Francis' decision to prepare for war and the army was mobilised. Austria and Prussia requested that Britain fund their military campaigns and requested a British military expedition to Germany. In April 1809 the British treasury supplied £20,000 in credit to Prussia, with additional funds promised if Prussia opened hostilities with France. Austria received £250,000 in silver, with a further £1 million promised for future expenses. Britain refused to land troops in Germany but promised an expedition to the low countries and to renew their campaign in Spain.
Austrian army and strategy with his staff at the Battle of Aspern-Essling, 21–22 May 1809 Austria built the largest
army in its nation's history, though its fighting quality was hampered by numerous factors. The men were conscripted from across the Austrian Empire and included Austrians, Hungarians, Czechs, Poles, Croats and Serbs; some, including the Hungarians, did not enthusiastically support their Austrian rulers. Conscription focused on the lower classes of society and the private soldiers, most of the non-commissioned officers, and many junior officers were illiterate. The army was well drilled in massed
column formations which were effective against cavalry but vulnerable to artillery fire, which hampered it in some battles of the campaign. The regular infantry were thought too slow-witted to be trained in skirmishing; this role had traditionally been filled by
grenzer light infantry units, but their quality declined since the potential conflicts with the Ottoman Empire ended. The deficiency was only partly remedied by recently created volunteer
jäger units. The Austrian militia, the
Landwehr, were intended as a home defence force but were moved to serve with the field army. The force was equipped with second rate weapons, were poorly trained, and forbidden to accept officers from the landowning classes, leading to poor leadership. They were used later in the war as
cannon fodder to divert French fire. The Austrian cavalry was of reasonably good quality, though in 1809 it was hampered by large numbers of its horses being only partly trained. The artillery was not as dynamic as in some contemporary armies, being placed under infantry commanders in the field and lacking proper
horse artillery to manoeuvre quickly. The Austrian army was supposed to be supplied by a large
wagon train, which restricted its manoeuvrability. Its senior officers were appointed based on aristocratic backgrounds and seniority, rather than ability; this led to elderly generals – the average being 63. The field commander, Archduke Charles, was unable to dismiss any of his commanders. He favoured doctrine over flexibility and expected his generals to follow a guide he had published in 1806. Charles and the
Aulic Council were divided on the best strategy for the coming war, Charles favoured an offensive launched from
Bohemia where there was a concentration of Austrian forces and an attack could quickly isolate the French in northern Germany. The Aulic Council disagreed because the
Danube river would split the forces of Charles and his brother
Archduke Johann of Austria. They suggested that the main attack should be launched south of the Danube to maintain safer communications with Vienna. In the end the Council prevailed but the disagreement delayed the Austrian preparations by a month. The Austrian plan called for the I Corps under
Heinrich Graf von Bellegarde, consisting of 38,000 troops, and the II Corps of 20,000 troops under
Johann Kollowrat, to attack
Regensburg (Ratisbon) from the Bohemian mountains by way of
Cham. The Austrian center and reserve, comprising 66,000 men of
Hohenzollern's III Corps,
Rosenberg's IV Corps, and
Lichtenstein's I Reserve Corps, would advance on the same objective through
Schärding. The left wing, made up of the V Corps of Archduke
Louis,
Hiller's VI Corps, and
Kienmayer's II Reserve Corps, a total of 61,000 men, would move toward
Landshut and guard the army's flank. Two other theatres would be opened in Poland and Italy. Historian Steven Englund considers that Austria "might well have won the campaign" if the nation had focused on Germany.
French preparations The
French army mostly consisted of veterans of Napoleon's earlier campaigns, though recent conscripts formed large parts of some units, negatively affecting their fighting ability. The army was enthusiastic and keen to fight well under Napoleon's direct leadership. Napoleon was not certain about Austrian planning and intentions. He returned to Paris from his campaigns in Spain in winter 1808–09 and instructed the main French field commander in southern Germany,
Louis Alexandre Berthier, on planned deployments and concentrations for this likely new second front. His rough ideas about the possible upcoming campaign included the decision to make the Danube valley the main theatre of operations, as he had done in 1805, and to stop Austrian forces that might invade
northern Italy by positioning some of his own forces under the command of
Eugène de Beauharnais and
Auguste Marmont. Faulty intelligence gave Napoleon the impression that the main Austrian attack would come north of the Danube. On 30 March, he wrote a letter to Berthier explaining his intention to mass 140,000 troops in the vicinity of Regensburg (Ratisbon), far to the north of where the Austrians were planning to make their attack. It was expected that this redeployment would take until mid-April to accomplish and Napoleon instructed Berthier that if the attack came before 15 April he was to fall back towards the
Lech. == Austria–Bavaria front ==