Kossak’s art was characterised by his admiration for horses, inherited from his father. As a soldier, he was profoundly acquainted with the realities of war. He was also thoroughly educated at European academies, thus demonstrating excellent painting skills. All of this allowed him not only to be comfortable with the realist painting conventions but also to create masterful and spectacular battlefield depictions.
Kossak co-authored four panoramas: Racławice, Berezina, The Battle of the Pyramids, and Somosierra, which was abandoned in the sketch phase. As a patriot, searching for heroic achievements and glorious moments in the history of his nation, he was fully predisposed to creating monumental historical paintings with dynamic, multi-layered action, embedded in a naturalistically reproduced landscape, and scrupulously representing bygone times, attire details, weapons, and military crafts.
A separate category in his painting output included hunting scenes, derived from the Munich art traditions, which referred to visual conventions employed by Juliusz Kossak and Maksymilian Gierymski (Imperial Hunting in Gödöllö, 1887; Par Force Hunting Chez Józef Potocki in Antoniny, 1909). In his series of genre scenes, mostly showing soldiers flirting with ladies, Kossak shined a light on his gift of observation of everyday events, revealing his dexterity in representing episodic scenes with a touch of humour (Trumpeter and a Blacksmith’s Wife, 1909, Wooing, 1927).
Kossak, criticised for ‘serial production’ of his paintings, i.e. creating increasing amounts of copies and compositional variations towards the end of his life, adopted a radically conservative position on the Polish art scene of the 1920s and 30s, standing in opposition not only to the avant-garde but also to the traditionalists propagating the idea of national art: Władysław Skoczylas and Władysław Teter. He created many of his late works in collaboration with his son Jerzy; he even signed some paintings conceived by Jerzy.
The thematic repertoire of his oeuvre was complemented by numerous self-portraits, idealised pictures of aristocratic and gentry women (Portrait of Zofia Hoesick, 1909), representational portraits of state dignitaries (Marshal Józef Piłsudski on Horseback, 1928), and of members of the financial elite and the intelligentsia.