Oil painting of Sitting Bull by Caroline Weldon, estimate $15,000-25,000 at Blackwell Auctions.

Enjoy unlimited access: just £1 for 12 weeks

Subscribe now

The military, spiritual and political leader, who united the Sioux people to defeat US General George Armstrong Custer at Little Big Horn in 1876, was befriended by artist and activist Caroline Weldon (1844-1921).

She had taken it upon herself to stand up for Indian rights and moved with her son to live with Sitting Bull and his family in 1889. Acting as secretary, among other roles for a brief period, a fictionalised account of their relationship was the subject of a 2017 movie, Woman Walks Ahead, with Jessica Chastain as Weldon.

Weldon fell out with Sitting Bull over the Ghost Dance movement that took hold in Indian Reservations in the summer of 1890. She argued the protest (dancing to reunite the living with spirits of the dead and end American expansion) would incite further violence from the government on the reservations. Following her departure her son died while they were travelling by riverboat to Missouri in the autumn of 1890.

Sitting Bull was murdered on December 15, 1890, shortly before the Massacre of Wounded Knee on December 29.

Of Weldon’s four portraits, one is held at the North Dakota Historical Society in Bismarck, while another is in the collection of the Historic Arkansas Museum in Little Rock. Two of the four were presumed lost until this version emerged.

Consigned by a descendant of the original owner, a railroad construction engineer from Minnesota, the oil painting is estimated at $15,000-25,000 at Blackwell Auctions in Clearwater, Florida, on March 18.