There are special items called War Banners that will allow you to attack
players from the opposite faction that do not have their Flag of War
raised if they are no more than three levels below you. However, it will
immediately allow any player from the opposite faction to attack you.
When you are under the effects of a War Banner, you will also earn twice
as much Combat Glory as normal. A War Banner will also affect any
allies that are near you, so they're best used when you're near a large
group of friends. War Banners can randomly be found on the corpse of any
monster in a contested zone, and can only be used in the contested zone
in which they were found.