This painting shows a Sioux warrior galloping on his paint horse. He is stripped for battle and throws caution to the wind. The eagle feather bonnet is a symbol of the Plains Indian and perhaps is over-used, but it seemed appropriate for this painting. The banner eagle wing staff tells us that he is an important member of the war party.
The white man would identify this staff as a flag. The eagle feather staff enabled the war party in a battle to locate the leader of the party. Each member of a war party was very independent and often it was every man for himself, but if the warriors had confidence in the ability of the leader, then they might follow his commands in battle. The construction of the eagle feather flag could be quite simple, and other times additional adornments could make the flag rather complex