The First Partition of Poland or First Partition of the Polish-Lithuanian Commonwealth took place in 1772 as the first of three partitions that ended the existence of the Polish-Lithuanian Commonwealth by 1795. The first partition was carried out by the Russian Empire, the Kingdom of Prussia and the Austrian Empire and was ratified by the Polish parliament (Sejm) in 1773 (see the Partition Sejm).
The First Partition occurred after the balance of power in Europe shifted, with Russian victories against the Ottomans in the Russo-Turkish War (1768–1774) strengthening Russia and endangering Habsburg interests in that region (particularly in Moldavia and Wallachia). From then on Habsburg Austria started to consider waging a war against Russia.
France, friendly towards both Russia and Austria, suggested a series of territorial adjustments, in which Austria would be compensated by parts of Prussian Silesia, and Prussia in turn would receive Polish Ermland (Warmia) and parts of Courland. King Frederick II of Prussia had no intention of giving up Silesia; he was, however, also interested in finding a peaceful solution — his alliance with Russia would draw him into a potential war with Austria, and the Seven Years' War had left Prussia's treasury and army weakened. He was also interested in protecting the weakening Ottoman Empire, which could be advantageously utilized in the event of a Prussian war either with Russia or Austria. Frederick's brother, Henry, spent the winter of 1770—71 as a representative of the Prussian court at Saint Petersburg. As Austria had annexed 13 towns in the Szepes region in 1769, Catherine and her advisor General Ivan Chernyshyov suggested to Henry that Prussia claim some Polish land, such as Ermland. After Henry informed him of the proposal, Frederick suggested a partition of the Polish borderlands by Austria, Prussia, and Russia, with the largest share going to the party most weakened by the recent changes in balance of power, Austria. Frederick attempted to encourage Russia to direct its expansion towards weak and non-functional Poland instead of the Ottomans. Kaunitz counter-proposed that Prussia take lands from Poland in return for relinquishing Silesia to Austria, but this plan was rejected by Frederick.
Although for a few decades (since the times of the Silent Sejm) Russia had seen weak Poland as its own protectorate, Poland had also been devastated by a civil war in which the forces of the Bar Confederation attempted to disrupt Russian control over Poland. Further, the Russian-supported Polish king, Stanisław August Poniatowski, was seen as both weak and too independent-minded; eventually the Russian court decided that the usefulness of Poland as a protectorate had diminished.
After Russia occupied the Danubian Principalities, Henry convinced Frederick and Maria Theresa that the balance of power would be maintained by a tripartite division of the Polish-Lithuanian Commonwealth instead of Russia taking land from the Ottomans. Under pressure from Prussia, which for a long time wanted to annex the northern Polish province of Royal Prussia, the three powers agreed on the First Partition of Poland. This was in light of the possible Austrian-Ottoman alliance with only token objections from Austria, which would have instead preferred to receive more Ottoman territories in the Balkans, a region which for a long time was coveted by the Habsburgs. The Russians also withdrew from Moldavia away from the Austrian border.
The regiments of the Bar Confederation, whose executive board had been forced to leave Austria (which previously supported them) after that country joined the Prusso-Russian alliance, did not lay down their arms. Many fortresses in their command held out as long as possible; Wawel Castle in Kraków fell only at the end of April; Tyniec fortress held until the end of July 1772; Częstochowa, commanded by Kazimierz Pułaski, held until late August. In the end, the Bar Conferation was defeated, with its members either fleeing abroad or being deported to Siberia by the Russians.
Despite token criticism of the partition from Austrian Empress Maria Theresa, Austrian statesman Wenzel Anton Graf Kaunitz considered the Austrian share an ample compensation; despite Austria being the least interested in the partition, it received the largest share of formerly Polish land and population. To Austria fell Zator and Auschwitz (Oświęcim), part of Little Poland embracing parts of the counties of Kraków and Sandomierz (with the rich salt mines of Bochnia and Wieliczka), and the whole of Galicia, less the city of Kraków.
Russia received the largest, but least-important area economically, in the northeast. By this "diplomatic document" Russia came into possession of the commonwealth territories east of the line formed roughly by the Dvina, Drut, and Dnieper rivers — that section of Livonia which had still remained in commonwealth control, and of Belarus embracing the counties of Vitebsk, Polotsk and Mstislavl.
By the first partition the Polish-Lithuanian Commonwealth lost about 30% of its territory, amounting at that time to about 733 000 km2, with a population of four million people (1/3 of its population), close to half of the country population before the partitions.
After having occupied their respective territories, the three partitioning powers demanded that King Stanisław August Poniatowski and the Sejm approve their action. The king appealed to the nations of Western Europe for help and tarried with the convocation of the Sejm. The European powers reacted to the partition with utmost indifference, only a few voices — like that of Edmund Burke — were raised in objection.
When no help was forthcoming and the armies of the combined nations occupied Warsaw to compel by force of arms the calling of the assembly, no alternative could be chosen save passive submission to their will. Those of the senators who advised against this step were threatened by the Russians, represented by the ambassador, Otto von Stackelberg, who declared that in the face of refusal the whole capital of Warsaw would be destroyed by them. Other threats included execution, confiscation of estates, and further increases of partitioned territory; some senators were arrested by the Russians and exiled to Siberia.
The local land assemblies (Sejmiks) refused to elect deputies to the Sejm, and after great difficulties less than half of the regular number of representatives came to attend the session led by Marshals of the Sejm, Michał Hieronim Radziwiłł and Adam Poniński; the latter in particular was one of many Polish nobles bribed by the Russians and following their orders. This sejm became known as the Partition Sejm. In order to prevent the disruption of the Sejm via liberum veto and the defeat of the purpose of the invaders, Poniński undertook to turn the regular Sejm into a confederated sejm, where majority rule prevailed. In spite of the efforts of individuals like Tadeusz Rejtan, Samuel Korsak, and Stanisław Bohuszewicz to prevent it, the deed was accomplished with the aid of Poniński, Radziwiłł, and the bishops Andrzej Młodziejowski, Ignacy Jakub Massalski, and Antoni Kazimierz Ostrowski (primate of Poland), who occupied high positions in the Senate of Poland. The Sejm elected a committee of thirty to deal with the various matters presented. On September 18, 1773, the committee formally signed the treaty of cession, renouncing all claims of the commonwealth to the lost territories.