Sada Kaur was married as a young woman to Gurbaksh Singh, son of Jai Singh Kanhaiya, chief of one of the Sikh misls, the confederate cavalry bands that divided control of Punjab in the eighteenth century before Ranjit Singh's unification. Her husband was killed in 1789 fighting a coalition of rival misls at the Battle of Batala, leaving her, still in her twenties, formally in command of the Kanhaiya Misl's territory and roughly eight thousand horsemen, an inheritance of military power that few women of the period held outright rather than as a nominal regent for a male heir.
Rather than retreat from that position, Sada Kaur used it. She arranged the marriage of her daughter Mehtab Kaur to Ranjit Singh, the young chief of the neighboring and smaller Sukerchakia Misl, and after his father's death in 1792 she effectively acted as his regent, combining the Kanhaiya cavalry with the Sukerchakia forces to give Ranjit Singh the military weight to begin absorbing rival misls one by one. Sikh historical accounts describe her personally leading troops into the field alongside him, including the 1799 campaign that took Lahore, the city that became Ranjit Singh's capital and the seat of the Sikh Empire he went on to found.
Without the Kanhaiya alliance she brought and sustained through nearly a decade of campaigning, Ranjit Singh's path from a minor misl chief to Maharaja of Punjab is difficult to account for, which is why oral historians in the Sikh tradition have called her the empire's true kingmaker even as formal history remembers her chiefly through her relationship to the man she helped make.