Complex sentence: His efforts to subdue them once more led to Sitting Bull's death and the massacre of about 300 Sioux, which included women and children at Wounded Knee on December 29,1890.
Split into simpler sentences: His efforts to subdue the Sioux led to Sitting Bull's death and the massacre of about 300 Sioux. This included women and children at Wounded Knee on December 29,1890.