The custom of flying flags dates to come back centuries, serving as a way of conversation on battlefields

https://mag-wiki.win/index.php/Marching_Through_Red_Cross_Month:_Flags_for_Medical_Heroes

The lifestyle of flying flags dates to come back centuries, serving as a way of conversation on battlefields. They conveyed messages of allegiance and victory, allowing armies to coordinate pursuits and options with out verbal communique.