Only high-grade Tier II players were allowed to join the battle. Reign knew that there would be many Tier I and Tier II demons present, but he didn't want to risk the weaker players dying on the battlefield simply because they were too weak.
He initially wanted to only allow Tier III players to join, but the players were adamant that he let the weaker ones fight as well as there were many of them that were in the high-grade and peak of Tier II inside the territory. They all wanted to help out and fight against the demons as this battle would probably mark the beginning of Doncaster's dominance in the entire region.