Post Civil War soldiers uniforms (calling CavGuy and others)

Sorry I missed this one! Been busy with RL type stuff and haven't been by for a while.

Sitting Bull's surrender was pretty late in the IW period, and I'd expect that you could find some good first-person accounts of the event. Anything informal would most likely have seen the soldiers in their normal duty uniforms (which would vary depending on the task they were assigned...cavalry troopers tended to wear white or gray canvas outfits for stable duty, for example). They'd be unbuttoned, and depending on the weather or day you might see a mix of military trousers and civilian shirts, for example. For the formal ceremony I'd be sure to check period accounts first, but it is quite possible that they'd be wearing their dress uniforms or Sunday inspection best (meaning a clean uniform that had never been worn in the field).

There wasn't necessarily a common practice for tribal surrenders (formal or informal). A great deal depended on the personality of the commander involved.