The Silesian Wars (German: Schlesische Kriege) were three wars fought in the mid-18th century between Prussia, under King Frederick the Great, and Habsburg Austria, under Empress 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 was a member of a coalition seeking territorial gain at Austria's expense. The Third Silesian War (1756–1763) was a theatre of the global Seven Years' War, in which Austria in turn led a coalition of powers aiming to seize Prussian territory.
No particular event triggered 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 victories, and the first resulted in 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, which would later culminate in the Austro-Prussian War of 1866.
Context and causes
In the early 18th century the Kingdom of Prussia's ruling House of Hohenzollern held dynastic claims to several duchies within the Habsburg province of Silesia, a populous and prosperous region contiguous with Prussia's core territory in the Margraviate 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, the Kingdom of Bohemia and the Margraviate of Moravia, and whichever power held the territory 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 the Polish–Lithuanian Commonwealth and of the Russian Empire within Germany.
Prussia's claims
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 feudal overlord) rejected the agreement and pressed the Hohenzollerns to repudiate it. In 1603, Hohenzollern Elector Joachim III Frederick of Brandenburg separately 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 1618 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 Hohenzollerns of Brandenburg continued to assert themselves as the legitimate rulers of Jägerndorf. In 1675 the "Great Elector" Frederick William 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 Bohemian 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 young prince, 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.
Austrian succession
Two generations later, the newly crowned Hohenzollern King Frederick II of Prussia formed designs on Silesia soon after succeeding to the 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 1737–1739 Austro-Turkish War. The European strategic situation was favourable for an attack on Austria, as Britain and France were occupying each other's attentions in the War of Jenkins' Ear, and Sweden was moving toward war with Russia. The Electors of Bavaria and Saxony also had claims against Austria and seemed likely to 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. 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 estates, but when he died it was promptly contested by Prussia, Bavaria and Saxony.
Moves toward war
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 not yet 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 the Poland-Lithuanian Commonwealth 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); Frederick's concern to prevent this outcome contributed to his haste in moving against Austria when the contested succession provided an opportunity.
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, lengthy sieges being 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.
First Silesian War
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 to Maria Theresa's husband, Duke Francis Stephen of Lorraine, in the forthcoming imperial election to replace the deceased Charles.
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 monarchy, 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. 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 Elector 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 and 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 was later formalised in the Treaty of Berlin.