"Jan Matejko (also known as Jan Mateyko; June 24, 1838, Free City of Kraków; - November 1, 1893, Kraków) was a Polish painter known for paintings of notable historical Polish political and military events. His most famous works include oil on canvas paintings like Battle of Grunwald, paintings of numerous other battles and court scenes, and a gallery of Polish kings. He is counted among the most famous Polish painters.
His painting The Battle of Grunwald is the cover art on Skill Challenges of War"
Source: Wikipedia, "Jan_Matejko", available under the CC-BY-SA License.