[The text is quite long, but you are able to glean a few details:]
Battle standards have been a necessary part of warfare in Pays-de-Ia-Gloire for at least three centuries: Once armies grew beyond a size where every lieutenant could stay within earshot of their captain, it became necessary for units to be able to identify one another from a distance, usually so that messengers carrying orders could be sure they were delivering them to the correct recipient. Banners commonly bear the heraldry of the House that owns them, or the personal arms of the unit commander, and there is commonly a strict order of precedence among banners which can even determine the deployment of a unit on the battlefield.