An essay examines Poland's distinctive social and political order and presents the life and career of a native king whose leadership played a decisive role in checking Ottoman incursions. It describes the deep divisions between nobles and peasants, the elective and constrained nature of the crown, and the ways factional liberties weakened central authority. The account follows the monarch's rise by personal merit, his military campaigns, and the persistent institutional and aristocratic obstacles he faced while attempting to defend and consolidate his country.