In June 1657, the Dano-Swedish War (1657–58) broke out, which forced Charles Gustav to move most of his army to Denmark. Under the circumstances, the Rakoczi decided to march southwards and leave the Commonwealth as soon as possible. Polish King John II Casimir of the Royal Vasa Dynasty was well aware of it and decided to prevent the Transylvanians, Moldovans, Wallachians, and Cossacks from escaping Poland. King John II Casimir called Stefan Czarniecki to come with his division to Częstochowa where Austrian cavalry mercenaries, Lithuanians of Aleksander Hilary Polubiński, and a unit of Crimean Tatars joined him. On 7 July, Czarniecki’s division reached Łańcut, where a council of Polish hetmans took place. Czarniecki followed Rakoczi, while Jerzy Sebastian Lubomirski and Stanisław "Rewera" Potocki sealed the Polish-Transylvanian border.
Battle
After the meeting, Czarniecki, with an army of 10,000. followed Rakoczi, attacking his troops in a guerrilla-style war, typical of the Polish hetman. On 11 July, Czarniecki attacked the Transylvanians, near the village of Magierów, north of Lwów. After a Polish attack, the Transilvanians retreated towards Żółkiew, leaving behind some 2,000 wagons with goods looted in Poland. Soon afterward, Poles ambushed the enemy in the swampy waterbed of the Poltva River. Hundreds of Hungarians drowned, and the survivors continued their retreat southwards.
Sources
Nagielski, Miroslaw (1990). Historyczne bitwy: Warszawa 1656 (in Polish). Bellona. ISBN83-11-07786-X.
Podhorodecki, Leszek (1985). Rapier i koncerz: Z dziejów wojen polsko-szwedzkich (in Polish). Ksiazka i Wiedza. ISBN9788305114523.