In 1740 Frederick “the Great” succeeded to the Prussian throne, and a few months later initiated the invasion and conquest of Silesia, the strategically important corridor between Poland and Saxony. This was to be the first act in the long series of Silesian wars.
Saxony was ruled at that time nominally by the Elector August II, but in practice by the wily Count Bruhl, whose handling of political matters was disastrous, his main talent being in plundering the State finances. It was due to his political vacillations that Saxony was drawn into the Second Silesian War, in which Leipzig was besieged and threatened with destruction.
A key figure among Frederick's generals was Leopold von Dessau, an aged combatant known as the “Old Dessauer” whom Frederick found somewhat difficult to manage, posting him for most of the campaigning years up to 1745 in command of an army of observation on the Saxon frontier.
The Old Dessauer was now over seventy, but his last campaign was destined to be the most illustrious of his long career. A combined effort of the Austrians and Saxons to mount a winter campaign and move towards Berlin led to a hurried concentration of the Prussian forces. Frederick managed to check the main Austrian army in Silesia, then hastened towards Dresden to take on the Saxons. But before he had arrived, Leopold, no longer in observation, had decided the war by his overwhelming victory over the Saxons at Kesselsdorf (December 14, 1745). It was his habit to pray before battle, for he was a devout Lutheran. On this last battlefield his words were, "O Lord God, let me not be disgraced in my old days. Or if Thou wilt not help me, do not help these scoundrels, but leave us to try it ourselves."
His successful taking of Leipzig was it must be admitted, somewhat facilitated by the practical burgers of Leipzig, who gallantly surrendered rather than have their fine city destroyed. The conquerors however made their point by occupying the Leipzig Garrison over Christmas 1745, withdrawing at the start of the New Year. On the instructions of the Leipzig City Council, Bach composed a celebratory/thanksgiving cantata, BWV 192 Nun Danket Alle Gott, which was performed on January 9th, 1746. Leipzig and Saxony were however required to pay onerous fines/reparations, impoverishing both city and state.
Just one example of the effects of the war are recorded in the history of the Saxon village of Nassau. A contract was signed in 1745 in which the congregation of Nassau village church committed themselves to an expense of 800 Taler for a new Silbermann organ, with 200 Taler in the church funds and little idea as to where they would find the rest. There was worse to come. With Prussia's invasion of Saxony in the Second Silesian War, the region found itself bearing the burden of some 2,000 Prussian soldiers, all of whom expected to be quartered and fed by the occupied inhabitants, incurring a final debt to the region estimated at some 3,000 Talers. Work began on the organ in the middle of April 1748, with completion and testing on August 4th of that same year. Precisely how the impoverished congregation was able to meet the payment is not recorded, save that the Over-Consistory in Dresden apparently came to the rescue.
Our contemporary drawing from 1746 shows the prudent burgers of Leipzig surrendering to Leopold.