Southern theater The first Russian forces crossed the border in Ukraine on the night of 18/19 May 1792. The Russians in that theater would encounter significantly more resistance than they expected, as Commonwealth's top commanders, Prince Poniatowski and Kościuszko were stationed there. Kościuszko joined Prince Poniatowski near Janów on 29 May. The Crown Army was judged too weak to oppose the four columns of enemy armies advancing into West Ukraine and began a fighting withdrawal to the western side of the
Southern Bug River, towards
Lubar and
Połonne, with Kośiuszko commanding the rear guard. Poniatowski, in the face of significant numerical inferiority of his forces, and promised reinforcements by King Poniatowski, decided to abandon Ukraine and move to
Volhynia, where Połonne was to be fortified as a major defensive point, and where Lubomirski was tasked with gathering supplies. '', by
Wojciech Kossak On 14 June Wielhorski's unit was defeated at the
Battle of Boruszkowce. On 17 June Poniatowski finally received awaited reinforcements, about 2,000 troops led by Michał Lubomirski. Next day the Poles, led by Prince Poniatowski, defeated one of the Russian formations of general
Irakly Morkov at the
Battle of Zieleńce on 18 June. The victory was celebrated by King Poniatowski, who sent the new
Virtuti Militari medals for the campaign leaders and soldiers, as "the first since
John III Sobieski". The Russian forces, however, kept advancing. Under the command of Józef Poniatowski, the Polish army retreated in good order, yielding to the more powerful enemy as necessary to avoid annihilation. In early July, near
Dubno, Prince Poniatowski and Kościuszko were betrayed by Michał Lubomirski, who was tasked with King Poniatowski with resupplying the troops; instead Lubomirski joined the Russian side and either hid the supplies for the Polish army, or outright passed them to the Russians. Lubomirski, however, was a powerful magnate, and it took until late May for the King officially to relieve him of his command. Within about a month of the Russian invasion, the Poles had mostly retreated from Ukraine. On 7 July Kościuszko's forces fought a delaying battle with the Russians at
Volodymyr (
Battle of Włodzimierz). Meanwhile, Poniatowski's army retreated to the
Bug River, where Kościuszko's units on 18 July fought the
Battle of Dubienka, which was a draw. With about 5,300 troops Kościuszko defeated the attack of 25,000 Russians under General
Mikhail Kakhovsky. Kośicuszko then had to retreat from Dubienka, as the Russians begun flanking his positions crossing the nearby Austrian border. Although the Poles had to retreat from the Bug River line, they were not defeated so far, and a decisive battle or battles at more favorable locations closer to Warsaw were expected.
Northern theater In the
Grand Duchy of Lithuania the Russians crossed the border four days later than in the south, on 22 May. Poland–Lithuania's ally, the
Kingdom of Prussia, broke its alliance with it and the Prussian commander of the Lithuanian army, Duke Württemberg, betrayed the Polish–Lithuanian cause by refusing to fight the Russians. He never reached the frontlines, feigned illness in
Wołczyn, and issued contradictory orders to his troops. Thus the Lithuanian army initially did little to oppose the advancing Russians, and kept withdrawing before their advance. Minsk was abandoned, after some skirmishes, on 31 May. Only after a change of commander on 4 June, did the Army, now under General
Józef Judycki, try to stand and fight the Russians. The Russians however defeated Judycki at the
Battle of Mir on 11 June and kept advancing through the Grand Duchy. The Lithuanian army retreated towards
Grodno. On 14 June the Russians took Vilnius, after only a small skirmish with local garrison; on 19 June, incompetently defended
Nieśwież; and on 20 June,
Kaunas, this time without any opposition. Judycki, disgraced, was replaced by
Michał Zabiełło on 23 June. Nonetheless, since Mir, no decisive engagements occurred in the northern theater, as the Lithuanian army withdrew in relative order towards Warsaw, after minor defeat at
Zelva, eventually taking defensive positions along the
Bug river near
Brest. Russians took Grodno on 5 July and Białystok on 17 July. On 23 July the Russians took Brest, defeating the local garrison, but on 24 they were defeated near
Krzemień-Wieś; this last battle was the first significant victory on the Lithuanian front.
War ends While Prince Poniatowski and Kościuszko considered the outcome of the war still open and were planning to use the combined Polish–Lithuanian forces to defeat the still separate Russian forces, King Poniatowski, with the consent of the
Guardians of the Laws (cabinet of ministers) decided to ask for a ceasefire. Tsarina Catherine demanded that King Poniatowski join the pro-Russian aristocratic faction, the Targowica Confederation; with his cabinet split, he gave in to her demand around 22–23 July, which effectively forced Prince Poniatowski to terminate military resistance. The last military confrontation of the war was fought on 26 July at
Markuszów in Lublin province, where an enemy attack was repelled by Polish cavalry led by Poniatowski. At the time King Poniatowski decided to sue for peace, the Polish army was still in a good fighting condition not having suffered from any major defeat nor lack of supplies. King Poniatowski thought that due to Russian numerical superiority defeat was nonetheless imminent, and more could be gained through negotiations with the Russians, with whom he hoped a new alliance could be formed. Although subsequent events would prove him wrong, the question of whether this could have been foreseen, and prevented through continued military resistance, has been
subject to much debate among historians. The Commonwealth's military was widely dissatisfied with the ceasefire; Kościuszko, Prince Poniatowski and many others would criticize the King's decision and many, including Kościuszko, would resign their commission in the coming weeks. Prince Poniatowski even considered rebelling against his uncle's orders, and even issued orders to bring the King to the army's camp by force if necessary, as was postulated by the more radical faction. Ultimately he decided not to continue fighting against his uncle's will, and the order was rescinded at the last moment before the departure of the group charged with capturing the King. ==Aftermath==