[9] In late 1742, while Prussia enjoyed the restored peace and worked to assimilate Silesia into its administration and economy,[10] Austria fought on against Bavaria and France, reversing its losses from 1741.

[11] By the middle of 1743 Austria had recovered control of Bohemia, driven the French back across the Rhine into Alsace, and occupied Bavaria, exiling Emperor Charles VII to Frankfurt.

[11] Prussia's withdrawal from the War of the Austrian Succession under a separate peace embittered its erstwhile allies,[12] and the diplomatic position shifted in Austria's favour.

The following year, Empress Elizabeth of Russia appointed as her chancellor Alexey Bestuzhev, a proponent of a pro-British and anti-French policy that entailed friendship to Austria and enmity to Prussia.

[17] Frederick decided that Prussia must restore its French alliance, build an anti-Austrian coalition with as many other German princes as possible, and then re-enter the war by striking first against Austria.

[19] On 22 May 1744 Prussia formed an alliance with Bavaria, Sweden, Hesse–Kassel and the Electoral Palatinate known as the League of Frankfurt, whose announced aim was to recover and defend the territories of Emperor Charles VII, including Bohemia (where he had been proclaimed king in 1742).

[19] As soon as the Franco–Bavarian threat from the west could be defeated, Austria intended to resume hostilities in Silesia and drive out the Prussians, restoring the borders of the territories Maria Theresa had inherited.

[27] 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.

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.

[35] Learning of the Austrians' rapid approach and unexpected strength, Frederick began pulling his forces back from south-eastern Bohemia to face the oncoming foes.

[39] Meanwhile, as Austrian forces withdrew from Bavaria to respond to the Prussian invasion of Bohemia, Emperor Charles VII recovered control of his capital at Munich, only to die shortly after relocating there on 20 January, destroying the rationale behind Frederick's alliance.

On 15 April the Austrians under Károly József Batthyány decisively defeated the Franco-Bavarian army at the Battle of Pfaffenhofen and drove the allied forces entirely out of Bavaria.

[39] After this defeat, Maximilian III Joseph, Elector of Bavaria (the son of the late Emperor Charles VII) made peace with Maria Theresa by the Treaty of Füssen on 22 April.

[41] In the treaty, Maximilian abandoned his father's claims on Austrian lands and promised to support Francis Stephen of Lorraine in the forthcoming imperial election; in return, Maria Theresa retroactively recognised Charles VII's legitimacy as Holy Roman Emperor.

Frederick abandoned the mountainous southern tip of Upper Silesia to the Austrian vanguard of pandurs,[42] concentrating his defences around the town of Frankenstein in the valley of the Eastern Neisse.

[42] The ensuing Battle of Hohenfriedberg ended in a decisive Prussian victory, sending Prince Charles's army retreating in disarray back into the mountains.

[41][44] The Prussians' supplies were exhausted, however, and they withdrew again into Upper Silesia for the winter, driving out the Austrian light troops that had entered the region ahead of Prince Charles's main force.

[49] Prussia and Britain hoped the Austrian defeats at Hohenfreidberg and Soor would persuade Austria to come to terms and concentrate its efforts against France, but Maria Theresa was resolved to fight on.

[53] On 15 December Leopold's force attacked and destroyed Rutowsky's army in the Battle of Kesselsdorf, opening the way to Dresden, as Prince Charles and the remaining Saxon soldiers retreated through the Ore Mountains into Bohemia.

Under the resulting agreement, Maria Theresa acknowledged Prussia's control of Silesia and Glatz, and Frederick retroactively recognised Francis I as Holy Roman Emperor and agreed to the Pragmatic Sanction,[54] while also committing to neutrality for the remainder of the War of the Austrian Succession.

[60] The small kingdom's unexpected victories over the Habsburg monarchy marked the beginning of Prussia's rise toward the status of a European great power, as it began to leave German rivals such as Bavaria and Saxony behind.

[67] The rest of the Habsburg patrimony in Central Europe was preserved intact, however, and Maria Theresa did win Prussia's retroactive support for her husband's election as Holy Roman Emperor.

[68] When the Treaty of Aix-la-Chapelle finally ended the wider War of the Austrian Succession in 1748, Maria Theresa's government refused to sign the peace agreement because it guaranteed Prussian sovereignty in the conquered province.

Instead, she began a general reform of Austria's military and a review of its diplomatic policy, all aimed at one day recovering Silesia and relegating Prussia to the status of a lesser power.