The Third Silesian War (German: Dritter Schlesischer Krieg) was a war between Prussia and Austria (together with its allies) that lasted from 1756 to 1763 and confirmed Prussia's control of the region of Silesia (now in south-western Poland). The war was fought mainly in Silesia, Bohemia and Upper Saxony and formed one theatre of the Seven Years' War. It was the last of three Silesian Wars fought between Frederick the Great's Prussia and Maria Theresa's Austria in the mid-18th century, all three of which ended in Prussian control of Silesia.
This conflict can be viewed as a continuation of the First and Second Silesian Wars of the previous decade. After the Treaty of Aix-la-Chapelle ended the War of the Austrian Succession, Austria enacted broad reforms and upended its traditional diplomatic policy to prepare for renewed war with Prussia. As with the previous Silesian Wars, no particular triggering event initiated the conflict; rather, Prussia struck opportunistically to disrupt its enemies' plans. The war's cost in blood and treasure was high on both sides, and it ended inconclusively when neither of the main belligerents could sustain the conflict any longer.
The war began with a Prussian invasion of Saxony in mid-1756, and it ended in a Prussian diplomatic victory with the 1763 Treaty of Hubertusburg, which confirmed Prussian control of Silesia. The treaty resulted in no territorial changes, but Austria agreed to recognise Prussia's sovereignty in Silesia in return for Prussia's support for the election of Maria Theresa's son, Archduke Joseph, as Holy Roman Emperor. The conflict formed part of the ongoing Austria–Prussia rivalry that would shape German politics for more than a century. The war greatly enhanced the prestige of Prussia, which won general recognition as a major European power, and of Frederick, who cemented his reputation as a preeminent military commander.
Context and causes
While the Seven Years' War was a global conflict among many belligerents, its Central European theatre turned on lingering grudges from the War of the Austrian Succession (1741–1748). The Treaty of Aix-la-Chapelle, which had concluded the latter war, confirmed Prussian King Frederick II's seizure of the region of Silesia from the Habsburg monarchy through two Silesian Wars. The defeated Empress Maria Theresa of Austria nevertheless fully intended to retake the lost province and reassert Austria's hegemony in the Holy Roman Empire; after peace was restored, she set about rebuilding her armed forces and seeking out new alliances.
Unresolved conflicts
Though France and Great Britain recognised Prussia's sovereignty in Silesia under the Treaty of Aix-la-Chapelle, Austria ultimately refused to ratify the agreement, and Maria Theresa's husband Francis I, Holy Roman Emperor, withheld the Holy Roman Empire's guarantee for Prussian control of the contested province. Prussia, in turn, withheld its assent to the Pragmatic Sanction, thus challenging Maria Theresa's legitimacy as head of the Habsburg monarchy. Despite dynastic links, British King George II viewed Prussia as an ally and proxy of the French, while Empress Elizabeth of Russia saw Frederick's kingdom as a rival for influence in the Polish–Lithuanian Commonwealth and feared that Prussia's growing power would obstruct the path of Russia's westward expansion. The political and diplomatic conditions that had led to the previous Silesian Wars still held, and further conflict seemed likely.
In 1746 Maria Theresa formed a defensive agreement with Elizabeth known as the Treaty of Two Empresses, which aligned Austria and Russia against Prussia; a secret clause guaranteed Russia's support for Austria's claims in Silesia. In 1750 Britain joined the anti-Prussian compact in return for guarantees of Austrian and Russian support in the case of a Prussian attack on the Electorate of Hanover, which George also ruled in personal union. At the same time, Maria Theresa, who had been disappointed with Britain's performance as her ally in the War of the Austrian Succession, followed the controversial advice of her Chancellor Wenzel Anton von Kaunitz by pursuing warmer relations with Austria's longstanding rival, the Kingdom of France.
Diplomatic Revolution
Britain elevated tensions in 1755 by offering to finance the deployment of a Russian army that would stand ready to attack Prussia's eastern frontier. Alarmed by this encirclement, Frederick began working to separate Britain from the Austrian coalition by allaying King George's concern for Hanover. On 16 January 1756 Prussia and Britain agreed to the Convention of Westminster, under which Prussia now undertook to guarantee Hanover against French attack, in return for Britain's withdrawal of its offer of military subsidies to Russia. This move created a new Anglo-Prussian alliance and incensed the French court.
Austria was now seeking warmer relations with France to ensure that the French would not take Prussia's side in a future conflict over Silesia. King Louis XV responded to Prussia's realignment with Britain by accepting Maria Theresa's invitation to a new Franco-Austrian alliance, formalised with the First Treaty of Versailles in May 1756. This series of political manoeuvres came to be known as the Diplomatic Revolution. Russia, likewise upset by the withdrawal of Britain's promised subsidies, drew closer to Austria and France, agreeing to a more openly offensive anti-Prussian coalition in April 1756. As France turned against Prussia and Russia separated from Britain, Kaunitz's plan thus matured into a grand anti-Prussian alliance between Austria, Russia, various lesser German powers, and France.
Preparations for war
As Austria and Russia made open preparations for renewed war, Frederick became convinced that Prussia would be attacked in early 1757. Rather than wait for his enemies to move at a time of their choosing, he resolved instead to act preemptively, beginning with an attack against the neighbouring Electorate of Saxony, which he correctly believed was a secret party to the coalition against him. Frederick's broad strategy had three parts. First, he meant to occupy Saxony, gaining strategic depth and using the Saxon army and treasury to bolster the Prussian war effort. Second, he would advance from Saxony into Bohemia, where he might set up winter quarters and supply his army at Austria's expense. Third, he would invade Moravia from Silesia, seize the fortress at Olmütz, and advance on Vienna to force an end to the war. He hoped to receive financial support from the British, who had also promised to send a naval squadron into the Baltic Sea to defend Prussia's coast against Russia, if necessary.
To begin, Frederick divided Prussia's armies in three. He placed a force of 20,000 under Field Marshal Hans von Lehwaldt in East Prussia to guard against any Russian invasion from the east, with a reserve of 8,000 standing in Farther Pomerania; Russia should have been able to bring irresistible force to bear against East Prussia, but the King trusted to the slowness and disorganisation of the Imperial Russian Army to defend his north-eastern flank. He also stationed Field Marshal Count Kurt von Schwerin in Silesia with 25,000 men to deter incursions from Moravia and Hungary. Finally, in August 1756 he personally led the main Prussian army of around 60,000 into Saxony, beginning the Third Silesian War.
Methods and technologies
European warfare in the early modern period was characterised by the widespread adoption of firearms in combination with more traditional bladed weapons. Eighteenth-century European armies were built around units of massed infantry armed with smoothbore flintlock muskets and bayonets. Cavalrymen were equipped with sabres and pistols or carbines; light cavalry were used principally for reconnaissance, screening and tactical communications, while heavy cavalry were used as tactical reserves and deployed for shock attacks. Smoothbore artillery provided fire support and played the leading role in siege warfare. Strategic warfare in this period centred around control of key fortifications positioned so as to command the surrounding regions and roads, with lengthy sieges a common feature of armed conflict. Decisive field battles were relatively rare, though they played a larger part in Frederick's theory of warfare than was typical among his contemporary rivals.
The Silesian Wars, like most European wars of the 18th century, were fought as so-called cabinet wars in which disciplined regular armies were equipped and supplied by the state to conduct warfare on behalf of the sovereign's interests. Occupied enemy territories were regularly taxed and extorted for funds, but large-scale atrocities against civilian populations were rare compared with conflicts in the previous century. Military logistics was the decisive factor in many wars, as armies had grown too large to support themselves on prolonged campaigns by foraging and plunder alone. Military supplies were stored in centralised magazines and distributed by baggage trains that were highly vulnerable to enemy raids. Armies were generally unable to sustain combat operations during winter and normally established winter quarters in the cold season, resuming their campaigns with the return of spring.
Course
1756
Invasion of Saxony
Prussian troops crossed the Saxon frontier on 29 August 1756. The Prussian Army marched in three columns: on the right were about 15,000 men under the command of Prince Ferdinand of Brunswick; on the left were 18,000 men under the command of the Duke of Brunswick-Bevern; in the centre was Frederick himself, with Field Marshal James Keith commanding a corps of 30,000 troops. Prince Ferdinand was to advance on the town of Chemnitz and proceed to Leipzig, while Bevern was to traverse Lusatia to seize Bautzen. Meanwhile, Frederick and Keith would advance through Torgau to attack the Saxon capital at Dresden. Saxony and Austria were unprepared for Frederick's preemptive strike, and their forces were scattered; as Prussians streamed into the Electorate, the main Saxon army fortified itself at Pirna, and the Prussians occupied Dresden on 9 September against little resistance.
Frederick and the main Prussian army pressed on into northern Bohemia, looking to engage the Austrians under General Maximilian Ulysses Browne before they could join forces with the Saxons. Browne took up a defensible position by the village of Lobositz, where the two forces fought the Battle of Lobositz on 1 October. The engagement ended inconclusively, with the Austrians inflicting significant losses on the Prussians and then retreating in good order; Frederick thus prevented Browne from reinforcing the isolated Saxons, but Browne stopped Frederick's advance into Bohemia. Turning back to the north, the Prussians fully occupied Saxony, even taking Elector Frederick Augustus II of Saxony prisoner, although he was allowed to withdraw to Poland on 18 October. The Saxon army was briefly besieged at Pirna and surrendered on 14 October, after which its men were forcibly incorporated into the Prussian army under Prussian officers. Saxony's treasury was emptied and its currency debased to help fund the Prussian war effort.
1757
Winter diplomacy
Over the winter of 1756–1757 the belligerents worked to secure their respective alliances and coordinate strategy with their allies. In February William Pitt, the new Leader of the House of Commons and a determined foe of France, persuaded the British Parliament to firmly and finally commit to the Prussian cause against Austria and France, after which Britain began delivering supplies and badly needed subsidies to Berlin. Parliament also approved the deployment of an Army of Observation to defend Hanover (and Brandenburg) against the coming French invasion from the west, and Frederick again called for a British naval deployment in the Baltic to deter Russia and an increasingly unfriendly Sweden, though nothing came of it.
However, Prussia's aggressive attack on Saxony galvanised the Austrian coalition, and in particular increased France's commitment to offensive war against Prussia. The Imperial Diet met in January in Regensburg, where Maria Theresa won enough German princes to her cause that the Holy Roman Empire declared war on Prussia on 17 January; the Diet called for a 40,000-man Reichsarmee to be assembled and put at Austria's disposal for the liberation of Saxony. In May 1757 the Second Treaty of Versailles strengthened the Franco-Austrian Alliance, with the French agreeing to contribute 129,000 soldiers to the fighting in Germany, along with subsidies of 12 million livres per year until Austria had recovered Silesia.
In return, Austria promised that after the victory was won it would grant France control of the Austrian Netherlands, a long-coveted prize for the French. Russia also committed 80,000 men to the conflict, hoping to seize East Prussia and then exchange that territory with Poland for control of Courland. Sweden also agreed to invade Prussian Pomerania, looking to recovering the territories lost to Prussia after the Great Northern War. In all, then, the Austrian coalition sought a total partition of the Kingdom of Prussia, all while portraying Frederick as the aggressor for making the first move to open war.