[2][3] His father, Krzysztof Czarniecki, was a soldier who participated in several wars in the late 16th and early 17th century, and eventually became a courtier to Polish queen Constance of Austria.

[1] The next time he took arms was in 1623, when his brother Paweł received a nomination as a rotmistrz of light (cossack) cavalry of the regular army (wojsko kwarciane), and recruited some of his siblings, including Stefan, into his unit.

[11] During those years, he learned much from observing a master of military arts, hetman Koniecpolski, who often commanded the Polish army in which he served, and from Poland's Swedish opponents, and earlier from the Cossacks and Tatars they fought.

[15] For his achievements in that war, in which he advanced to a porucznik rank in the light "cossack" cavalry unit under hetman Marcin Kazanowski, he received some land in the Smolensk Voivodeship near Starodub.

[1][15] After that war, he moved to a more prestigious hussar unit (rota), and likely due to a reduction of the royal army, he served in the private formation of Władysław Myszkowski and later, voivode Stanisław Lubomirski.

[17] In 1637 he married Zofia Kobierzycka,[18] and later that year he fought in the Pawluk Uprising against the rebellious Cossacks under Pavel Mikhnovych, participating in the battle of Kumejki.

[16][20] In 1644 under Koniecpolski he took part in the battle of Ochmatów where Commonwealth forces dealt a crushing defeat to Toğay bey's (Tuhaj Bej) Tatars.

[16] He served as one of seven pułkowniks in Koniecpolski's army, and once again his cavalry unit charge proved to be a decisive moment of the battle, bringing him much fame.

[22] According to Nagielski, Czarniecki, while returning from the Sejm, witnessed the massacre of Polish prisoners in the aftermath of the battle of Batoh;[22] This scene made him reject the notions that a compromise with the enemies of the Commonwealth was a likely or desired outcome.

[28] At that time his reputation was significant; Sejm often passed resolutions applauding him for his efforts to reclaim Ukraine, and he was even held in much consideration by the Ottomans, then temporarily allied with the Commonwealth.

[28] From Autumn of 1654 to Spring of 1655 during the "Bracław Campaign" Stefan Czarniecki's army with the support of Crimean Tatars murdered 100,000 Ukrainians[29] some sources even put the number as high as 300,000.

[30] When Charles X of Sweden invaded Poland in 1655, Czarniecki distinguished himself by his defence of Kraków, which he eventually surrendered on good terms, retreating with his army.

[28] He led guerrilla warfare against Swedish troops of Charles X, a type of a campaign he authored, despite the objections of the hetmans, who by that time returned to serve under John Casmimir Vasa.

[1][36] The Field Crown Hetmanship went to Jerzy Sebastian Lubomirski, also an accomplished commander, if not so much as Czarniecki – but from a magnate Lubomirski family; Czarniecki commented famously that "Not of salt, or fields, I am, but from what hurts me", alluding to the fact that Lubormirski family built its fortune on salt trade and agriculture, whereas his smaller one was built through military service – yet it was money and politics, not military experience, that decided who was to get the hetman's office.

[36] On the conclusion of the Peace of Oliwa, which adjusted the long outstanding differences between Poland and Sweden, Czarniecki was transferred to the eastern frontier where the war with Russia reignited.

[39] His reputation among the unpaid and dissenting military took a dive; and many criticized him for appropriating the entire ransom that the Russians paid for their prisoners from Połonka.

He led an army against the Russians, but the Siege of Hlukhiv was not successful, and a new Cossack uprising of Ivan Sirko forced the Polish troops to fall back.

[41] Called back by the king, who feared that magnate Jerzy Sebastian Lubomirski that he just banished might start a rebellion, his recent wound became infected, and he died on 16 February 1665 in Sokołówka (now Sokolívka) near Lwów, six weeks after receiving this supreme distinction.

[42] Jak Czarniecki do Poznania Po szwedzkim zaborze, Dla ojczyzny ratowania Wrócim się przez morze.

[49] That legend that became even stronger during the times of the partitions of Poland in the 19th century, where the artists of the Polish romanticism period used him as a symbol of patriotism, and a reminder of military successes.