Following the Union of Lublin (1569), Bielsko was transferred from Grand Duchy of Lithuania into the Kingdom of Poland. Bielsk was a royal town of Poland, administratively located in the Podlaskie Voivodeship in the Lesser Poland Province of the Polish Crown. The town prospered, with churches, hospital, mills, shops and 265 artisans (as for 1576). Bielsko burned in 1591, and Swedish invasion of Poland brought almost complete destruction (1655).