"From now on, cats must be loyal only to their own Clanmates. Friendships with cats from another territory must be put aside for the sake of their Clan. We cannot allow our warriors to be distracted in battle or to fight for anything other than what is best for their own Clan. Are we agreed?"
Duststar, angry about RiverClan accusing WindClan of stealing fish, leads a battle against them and when the terrible battle is over, Duststar comes up with the first rule of the warrior code after Ryewhisker dies: that each cat must defend its Clan, even with their life, and that a cat must remain loyal to their Clan, as one day they may meet their friends in battle, referring back to the connection and bond between Ryewhisker and Cloudberry.
Birchstar suggests a truce, which later develops into the present-day Clans' standard Gathering, he strongly shows his agreement for the idea. He is shown to be very wise, not blaming Emberstar, the RiverClan leader, for the death of Ryewhisker, and instead creating a law that would help it be avoided. He, along with the other Clan leaders, establish a significant aspect of the warrior code that will last for generations to come.
"Cats of all the Clans! From now on you must defend your Clan, even with your life. You may have friendships with cats from other Clans, but your loyalty must remain to your Clan, as one day you may meet cats you have befriended in battle. This will be our code, the law of warriors, and it is up to each one of us to carry it in our hearts."
—Duststar telling every cat of every Clan about the new rule Code of the Clans, page 18