Battle of Seret

In January 1538, Petru Rareș's Moldavian army invaded the south-eastern lands of the Kingdom of Poland. He looted settlements and castles such as Jagielnica, Satanów, Czerwone [pl] and Zinkowie [pl].

Moldavian voivode Petru Rareș led a 20,000-strong army, while Polish commanders Mikołaj Sieniawski and Andrzej Tęczyński assembled a winter defense army of 6,000 troops, including 17 cavalry banners (1,800 horsemen), which were supposed to take on the main fighting on 1 February.^[1][2] The Polish army was divided into two groups on a steep bank, near Seret, with left wing led by Andrzej Tęczyński and right by Mikołaj Sieniawski.^[3] However, the Polish forces were in an unfavorable position, as they fought during winter on a frozen banks of Seret river and were outnumbered by Moldavians.^[1][2] The course of the battle isn't known, but the Moldavians likely outflanked the Poles, used heavy bow fire against the Polish troops, with Polish cavalry stuck in the mud or falling into ravine, forcing the rest of the army to flee and survivors to descend cross the frozen Seret river.

The battle resulted in Moldavian victory and was considered to be the biggest Polish defeat in a border conflict for its time.^[1][2] The Polish army suffered 900 killed and many captured, including 800 pocztowy [pl] and 80 towarzysze falling in battle, alongside captains Jan Pilecki [pl] killed and Maciej Włodek [pl] captured.^[1][2][4] Polish chronicler Marcin Bielski blamed the defeat on the poor leadership of Mikołaj Sieniawski and Andrzej Tęczyński, which chose to fight a numerically superior enemy in an unfavorable environment.^[4]

Despite the Moldavian tactical success, Petru Rareș decided to renounce his claims to Pokuttia and end the war with Poland, as he was threatened by the Ottoman Empire from the south and didn't want to fight a two front war against both the Kingdom of Poland and the Ottoman Empire.^[5]

• Plewczyński, Marek (2017). Wojny i wojskowość polska w XVI wieku: Lata 1500-1548 [Polish wars and military in the 16th century: 1500-1548] (in Polish). Vol. 1. Oświęcim: Wydawnictwo Napoleon V. ISBN 9788365746382.