Initially a lukewarm member of the Polish Reformed Church, under the influence of Jesuits and his first wife he converted from Calvinism to Catholicism. Potocki was married to Zofia Kalinowska and Anna Mohyła. After careful studies at home and abroad (mostly in France and in the Netherlands) he began his great military career by fighting the rebels with his father and uncles on the side of King Sigismund III at the Battle of Guzów. He then took part in an expedition to Wallachia and in the siege of Smolensk in 1611, during the Polish-Russian war. He also fought in Cecora (1620) and Chocim (1621). He took part in the war with Sweden (1626–1629) temporarily replacing Stanisław Koniecpolski who suffered a major defeat at Górzna in 1629. He fought the rebellious Cossacks in the years 1637–1638.