The Silesian Wars (German: Schlesische Kriege) were a series of three wars fought in the mid-18th century between Prussia (under King Frederick the Great) and Austria (under Archduchess Maria Theresa) for control of the Central European region of Silesia (now in south-western Poland). The First (1740-1742) and Second (1744-1745) Silesian Wars formed parts of the wider War of the Austrian Succession, in which Prussia acted as one member of a coalition seeking territorial gain at Austria's expense. The Third Silesian War (1756-1763) was one theatre of the global Seven Years' War, in which Austria in turn led a coalition of powers aiming to seize Prussian territory.
No particular triggering event caused the wars. Prussia cited its centuries-old dynastic claims on parts of Silesia as a casus belli, but Realpolitik and geostrategic factors also played a role in provoking the conflict. Maria Theresa's contested succession to the Habsburg Monarchy under the Pragmatic Sanction of 1713 provided an opportunity for Prussia to strengthen itself relative to regional rivals such as Saxony and Bavaria.
All three wars are generally considered to have ended in Prussian victory, and their territorial result was Austria's cession of the majority of Silesia to Prussia. Prussia emerged from the Silesian Wars as a new European great power and the leading state of Protestant Germany, while Catholic Austria's defeat by a lesser German power significantly damaged the House of Habsburg's prestige. The conflict over Silesia foreshadowed a wider Austro-Prussian struggle for hegemony over the German-speaking peoples that would later culminate in the Austro-Prussian War of 1866.
In the early eighteenth century Brandenburg-Prussia's ruling House of Hohenzollern held dynastic claims to various duchies within the Habsburg province of Silesia, a populous and prosperous region contiguous with Prussia's core territory of Brandenburg. Besides its value as a source of tax revenue, industrial output and military recruits, Silesia held great geostrategic importance to multiple parties. The valley of the Upper Oder formed a natural military conduit between Brandenburg, Bohemia and Moravia, and whichever power held it could threaten its neighbours. Silesia also lay along the north-eastern frontier of the Holy Roman Empire, allowing its controller to limit the influence of Poland and Russia within Germany.
Brandenburg-Prussia's claims in Silesia were based, in part, on a 1537 inheritance treaty between the Silesian Piast Duke Frederick II of Legnica and the Hohenzollern Prince-Elector Joachim II Hector of Brandenburg, whereby the Silesian Duchies of Liegnitz, Wohlau and Brieg were to pass to the Hohenzollerns of Brandenburg should the Piast dynasty in Silesia become extinct. At the time, the Habsburg King Ferdinand I of Bohemia (Silesia's legal overlord) rejected the agreement and pressed the Hohenzollerns to repudiate it. In 1603, Hohenzollern Elector Joachim III Frederick of Brandenburg also inherited the Silesian Duchy of Jägerndorf from his cousin, Margrave George Frederick of Brandenburg-Ansbach, and installed his second son, Johann Georg, as duke.
In the Bohemian Revolt and the ensuing Thirty Years' War, Johann Georg joined the Silesian estates in revolt against the Catholic Holy Roman Emperor Ferdinand II. After the Catholic victory in the 1621 Battle of White Mountain, the Emperor confiscated Johann Georg's duchy and refused to return it to his heirs after his death, but the Electors of Brandenburg continued to assert themselves as the legitimate rulers of Jägerndorf. In 1675 the "Great Elector" Frederick William of Brandenburg laid claim to Liegnitz, Wohlau and Brieg when the Silesian Piast line ended with the death of Duke George William of Liegnitz, but the Habsburg Emperor disregarded the Hohenzollern claims and the lands escheated to the crown.
In 1685, when Austria was engaged in the Great Turkish War, Emperor Leopold I gave Great Elector Frederick William immediate control of the Silesian exclave of Schwiebus in return for military support against the Turks and the surrender of the outstanding Hohenzollern claims in Silesia. After the accession of the Great Elector's son and successor, Frederick III of Brandenburg, the Emperor took back control of Schwiebus in 1694, claiming that the territory had only been personally assigned to the late Great Elector for life. As a youth, Frederick III had secretly agreed to this repossession in return for Leopold's payment of some of his debts, but as monarch he repudiated the agreement and reasserted the old Hohenzollern claims to Jägerndorf and the Silesian Piast heritage.
Two generations later, the newly crowned Hohenzollern King Frederick II of Prussia formed designs on Silesia soon after succeeding to the Prussian throne in May 1740. Frederick judged that his dynasty's claims were credible, and he had inherited from his father a large and well trained Prussian army and a healthy royal treasury. Austria was in financial distress, and its army had not been reinforced or reformed after an ignominious performance in the recent Austro-Turkish War. The European strategic situation was favourable for an attack on Austria, with Britain and France occupying each other's attentions and Russia in conflict with Sweden;Bavaria and Saxony also had claims against Austria and might join in the attack. Though the Hohenzollerns' dynastic claims provided a legalistic casus belli, considerations of realpolitik and geostrategy played the leading role in provoking the war.
An opportunity arose for Brandenburg-Prussia to press its claims when Habsburg Holy Roman Emperor Charles VI died in October 1740 without a male heir. With the Pragmatic Sanction of 1713, Charles had established his eldest daughter, Maria Theresa, as the successor to his hereditary titles, and upon his death she duly became ruler of Austria, as well as of the Bohemian and Hungarian lands within the Habsburg Monarchy. During Emperor Charles's lifetime, the Pragmatic Sanction was generally acknowledged by the imperial states, but when he died it was promptly contested by several parties.
Frederick saw in Austria's female succession an opportune moment for the seizure of Silesia, calling it "the signal for the complete transformation of the old political system" in a 1740 letter to Voltaire. He argued that the Pragmatic Sanction did not apply to Silesia, which was held by the Habsburgs as a part of the imperial demesne rather than as a hereditary possession. Frederick also argued that his father, King Frederick William I, had assented to the Sanction in return for assurances of Austrian support for Hohenzollern claims on the Rhenish Duchies of Jülich and Berg, which had never materialised.
Meanwhile, Prince-Elector Charles Albert of Bavaria and Prince-Elector Frederick Augustus II of Saxony had each married one of Maria Theresa's older cousins from a senior branch of the House of Habsburg, and they used these connections to justify claims to Habsburg territory in the absence of a male heir. Frederick Augustus, who ruled Poland in personal union, was especially interested in gaining control of Silesia to connect his two realms into one contiguous territory (which would nearly surround Brandenburg); concern to prevent this outcome contributed to Prussia's haste in moving against Austria when the contested succession provided an opportunity.
After Emperor Charles's death on 20 October 1740, Frederick quickly resolved to strike first; on 8 November he ordered the mobilisation of the Prussian army, and on 11 December he issued an ultimatum to Maria Theresa demanding the cession of Silesia. In return, he offered to guarantee all other Habsburg possessions against any attack, pay a large cash indemnity, acknowledge the Pragmatic Sanction, and give his vote as elector of Brandenburg in the imperial election to Maria Theresa's husband, Duke Francis Stephen of Lorraine.
Not waiting for a response, and without a declaration of war, he led Prussian troops across the lightly defended Silesian frontier on 16 December, beginning the First Silesian War. By the end of January 1741 almost the entirety of Silesia was under Prussian control, and the remaining Austrian strongholds of Glogau, Brieg and Neisse were besieged. In late March an Austrian force relieved the siege of Neisse, but the main Prussian force engaged and defeated it in the Battle of Mollwitz on 10 April, securing Prussian control of the region.
Seeing Austria's defeat at Mollwitz, other powers were emboldened to attack the beleaguered archduchy, widening the conflict into what would become the War of the Austrian Succession. As Bavaria, Saxony, France, Naples and Spain attacked Austria on multiple fronts during the succeeding months, Frederick began secret peace negotiations with Maria Theresa, with British urging and mediation; on 9 October Austria and Prussia agreed to a secret armistice known as the Convention of Klein-Schnellendorf, under which Austria committed to eventually concede Lower Silesia in return for peace.
As Austria concentrated its forces against its other enemies and gained ground in the wider war, Frederick concluded that the Austrians did not intend to honour the Convention and concede territory in Silesia, so, to press Austria further, he repudiated the armistice and renewed offensive operations of his own. In December 1741 Prussian forces advanced into Moravia, occupying the capital at Olmütz, and besieged the fortress at Glatz on the edge of Bohemia. In January 1742 Duke Charles Albert of Bavaria won the 1742 Imperial election and became Holy Roman Emperor. In February Frederick organised a joint advance through Moravia toward Vienna with the Saxons and French, but Prussia's allies were reluctant and uncooperative, and the campaign was abandoned in April, after which the Prussians withdrew into Bohemia and Upper Silesia.
An Austrian counter-advance into Bohemia engaged Frederick's Prussians on 17 May and was narrowly defeated at the resulting Battle of Chotusitz. This defeat left Austria with no immediate means of driving its enemies out of Bohemia, and renewed peace talks with Prussia began in Breslau. Under British pressure, Austria agreed to cede to Prussia the large majority of Silesia, along with the County of Glatz in Bohemia, while Austria would retain two small portions of the extreme southern end of Silesia, including the Duchy of Teschen and parts of the Duchies of Jägerndorf, Troppau, and Neisse. Prussia also agreed to take on some of Austria's debts, as well as committing to remain neutral for the remainder of the ongoing war. This peace agreement was adopted with the Treaty of Breslau, which ended the First Silesian War on 11 June 1742, and soon after formalised in the Treaty of Berlin.
Peace with Prussia allowed the Austrians and their British-Hanoverian allies to reverse the gains made by the French and Bavarians in 1741. By mid 1743 Austria recovered control of Bohemia, drove the French back across the Rhine, and occupied Bavaria. In September 1743 Britain, Austria and Savoy-Sardinia concluded a new alliance under the Treaty of Worms that led Frederick to suspect that Maria Theresa meant to retake Silesia as soon as the war elsewhere was concluded. So, on 7 August 1744 Prussia declared its intervention in the ongoing conflict on behalf of Emperor Charles Albert, and Frederick led soldiers across the frontier into Bohemia on 15 August, beginning the Second Silesian War.
Prussian forces converged upon Prague, seizing the city on 16 September, and this new threat drew the Austrian army back from France through Bavaria. The French, however, failed to harass and disrupt the Austrian redeployment, so Austria's army was able to return to Bohemia quickly and at full strength. Frederick gathered his forces around Prague and tried to force a decisive engagement, but Austrian commander Otto Ferdinand von Traun focused on harassing the invaders' supply lines, eventually forcing the Prussians to abandon Bohemia and retreat into Upper Silesia in November.
With the January 1745 Treaty of Warsaw, Austria established a new "Quadruple Alliance" between Austria, Britain, Saxony, and the Dutch Republic. Meanwhile, Emperor Charles Albert died on 20 January, destroying the rationale behind Frederick's alliance. Austria renewed its offensive against Bavaria in March 1745, decisively defeating the Franco-Bavarian army at the 15 April Battle of Pfaffenhofen, and making peace with Maximilian III of Bavaria (the son of the late Emperor Charles Albert) by the Treaty of Füssen on 22 April.
Having defeated Bavaria, Austria began an invasion of Silesia. At the end of May an Austrian-Saxon army crossed through the Giant Mountains into Silesia, only to be surprised and decisively defeated by Frederick in the Battle of Hohenfriedberg on 4 June, removing any immediate prospect of Austria's recovering Silesia. The Prussians followed the retreating Austrian-Saxon army into Bohemia, encamping along the Elbe while Frederick pursued a peace agreement. During the following months Maria Theresa won the support of enough prince-electors to see her husband named Holy Roman Emperor Francis I on 13 September in Frankfurt, achieving one of her major goals in the war.
On 29 September the Austrians attacked Frederick's camp in Bohemia, resulting in a Prussian victory at the Battle of Soor, despite the Austrian surprise and superior numbers. After this, low supplies forced the Prussians to withdraw into Upper Silesia for the winter. In November Austria and Saxony prepared a surprise double invasion of Brandenburg, hoping together to seize Berlin and end the war outright. On 23 November Frederick surprised the Austrian invaders in the Battle of Hennersdorf, confusing and scattering the larger Austrian force. Meanwhile, another Prussian army under Leopold I of Anhalt-Dessau advanced into western Saxony, attacking and destroying the main Saxon army in the Battle of Kesselsdorf on 15 December, after which the Prussians occupied Dresden.
In Dresden the belligerents quickly negotiated a peace treaty, under which Maria Theresa recognised Prussian sovereignty in Silesia and Glatz, while Frederick acknowledged Francis I as Holy Roman Emperor and again committed to neutrality for the remainder of the War of the Austrian Succession. For its part in the Austrian alliance, Saxony was compelled to pay one million rixdollars in reparations to Prussia. The region's borders were thus confirmed at the status quo ante bellum, which had been Prussia's principal goal. This Treaty of Dresden was signed on 25 December 1745, ending the Second Silesian War between Austria, Saxony, and Prussia.
After Austria's defeat in the previous Silesian Wars, Maria Theresa was determined to rebuild her armed forces and form new alliances that could enable her to retake her lost province of Silesia. In 1756 these efforts led Austria to abandon its alliance with Britain in favour of a new Franco-Austrian alliance, prompting a diplomatic reordering of the European powers known as the Diplomatic Revolution. As Austria, France and Russia formed a new anti-Prussian coalition, Frederick once again chose to strike first: on 29 August 1756 he preemptively invaded neighbouring Saxony, beginning the Third Silesian War.
As Austria's and Prussia's allies joined the fighting, the conflict quickly widened into what became the pan-European Seven Years' War. The Prussians occupied Saxony in late 1756 and made large advances in Bohemia in early 1757, winning a series of battles while advancing to Prague. In May Prussian forces took great losses while driving back the Austrian defenders in the Battle of Prague and then besieged the city. An Austrian counter-attack culminated in the major Austrian victory at the Battle of Kolín on 18 June, which drove the Prussians out of Bohemia entirely. Meanwhile, Russian and Swedish invasions from the east and north divided Prussia's forces. The Russian invaders in East Prussia won the Battle of Gross-Jägersdorf on 30 August, but they made little strategic progress due to recurring logistical problems.
In late 1757 Imperial and French forces attempted to retake Saxony from the west, only to experience a decisive defeat in the Battle of Rossbach on 5 November. This battle secured Prussia's control of Saxony for a time, and the defeat greatly reduced French willingness to contribute further to the Silesian War. Another Austrian army invaded Silesia, making significant progress until it was decisively defeated at the Battle of Leuthen on 5 December, after which the Prussians pursued the defeated Austrian army back to Bohemia and recovered control of nearly all of Silesia. Over the winter a combined Prussian-Hanoverian army launched a series of offensives that eventually drove the French out of Westphalia and across the Rhine, securing Prussia's western flank for the duration of the war.
In mid-1758 Prussia invaded Moravia, besieging Olmütz in late May. The city was well defended, and by late June the Prussians' supplies were exhausted. Austrians intercepted and destroyed a major Prussian supply convoy on 30 June in the Battle of Domstadtl, and the invaders abandoned the siege, retreating into Upper Silesia. Russian forces advanced through East Prussia to threaten Brandenburg, fighting the Prussians to a costly draw on 25 August at the Battle of Zorndorf. An Austrian army advancing into Saxony made little progress, despite winning a substantial victory at the Battle of Hochkirch on 14 October.
In 1759 a united Austrian and Russian advance into eastern Brandenburg culminated in a major Prussian defeat at the Battle of Kunersdorf on 12 August, but the victorious allies did not pursue the defeated Prussians or occupy the Prussian capital at Berlin. After Kunersdorf Frederick had briefly believed the war totally lost, but the coalition's internal conflicts and hesitant leadership gave Prussia a second chance, an event that Frederick later termed the "Miracle of the House of Brandenburg." The succeeding months saw the Austrians retake Dresden and most of Saxony, with intermittent skirmishing in Saxony through the end of the year.
In 1760 the Austrians advanced into Lower Silesia, where the Prussian and Austrian armies manoeuvred against each other for some time before engaging in the Battle of Liegnitz on 15 August; the battle ended in a solid Prussian victory, disrupting the Austrians' advance and restoring Prussian control of Lower Silesia. In late 1760 the Russians and Austrians briefly occupied Berlin, and on 3 November the main Prussian and Austrian armies fought the Battle of Torgau, a narrow Prussian victory that proved costly for both sides. 1761 saw little activity by the exhausted Prussian and Austrian forces, but Russian forces made advances in Pomerania and eastern Brandenburg which threatened a decisive end to the war the following year.
In January 1762, however, Austria was suddenly abandoned by its chief ally upon the death of Empress Elizabeth of Russia. She was succeeded by the ardently pro-Prussian Peter III of Russia, who immediately recalled his armies from Berlin and Pomerania and made peace with Prussia by the Treaty of Saint Petersburg on 5 May. Peter was himself overthrown and assassinated within months, but by then the war had again shifted in Prussia's favour, and Russia did not resume hostilities. Both sides were nearing exhaustion, and peace talks to end the wider Seven Years' War began in late 1762. In the end, negotiators agreed again on a return to the status quo ante bellum, confirming Prussia's control of Silesia in the Treaty of Hubertusburg in February 1763. Prussia also committed to support the election of Maria Theresa's son, Archduke Joseph, as Holy Roman Emperor.
The Silesian Wars ended in Prussian victory over Austria, a view universal among contemporaries and broadly supported by historiography since. Prussia seized and defended a long-held Habsburg territory, and the status quo ante outcomes of the second and third wars confirmed this basic fact. The small kingdom secured some 35,000 square kilometres (14,000 sq mi) of new territory and around a million new subjects, greatly enhancing its resources and prestige. These conflicts provoked a broad realignment in the European diplomatic system of the time, establishing an Austria-Prussia rivalry that would define German politics for a century until after the Austro-Prussian War of 1866.
Prussia's unexpected victory over the Habsburg Monarchy set it apart from German rivals such as Bavaria and Saxony, marking Prussia's rise to the status of a great power whose importance in Europe could no longer be disputed, as well as the leading power of Protestant Germany. The kingdom had gained control of extensive new lands in Glatz and Silesia, a region both populous and densely industrialised that would contribute substantial manpower and taxes to the Prussian state. Geostrategically, Silesia also gave Prussia a threatening position with respect to Saxony and Austria and a strong defence against encirclement by Poland.
Frederick's personal reputation was enormously enhanced by his successes in the wars, winning him the epithet "Frederick the Great". His debts to fortune, such as Russia's about-face after Elizabeth's death, and to foreign financial support were soon forgotten, while the memories of his energetic leadership and tactical genius were strenuously promoted. His small kingdom had defeated the Habsburg Monarchy and defended its prize against Austria, Britain, Saxony, Russia, Sweden, and (briefly) France, an accomplishment that appeared miraculous to contemporary observers.
The defeats of the Silesian Wars cost the Habsburg Monarchy its wealthiest province, and capitulating to a lesser German prince significantly dented the House of Habsburg's prestige. Prussia's confirmation as a first-rate power and the enhanced prestige of its king and army were long-term threats to Austria's hegemony in Germany. Indeed, the Empire now held several ambitious middle powers eager to gain at Austria's expense, including Saxony, Bavaria, and Hanover. The Silesian Wars made clear that the Habsburg Monarchy would need significant reform if it was to retain its dominant position in European power politics.
Still, by winning Prussia's support for the imperial elections of her husband and son, Maria Theresa ensured the continuation of her family's titular preeminence in the Holy Roman Empire. Defeat at the hands of an enemy so apparently inferior created a strong impetus for change within the Austrian administration, resulting in broad military reforms and a total realignment of Habsburg foreign policy through the "Diplomatic Revolution." The struggle with Prussia would become the driving factor behind wide-ranging efforts to modernize the Habsburg Monarchy over the next half century through a series of military, educational and administrative reforms.