With the sudden changes, the entire academy had been turned into a base for the army. But they weren't immediately sent out to fight.
Groups of twenty were set up with equal members of martial artists and mages across all classes.
They also made sure that they set people who knew each other up at the very least. The army didn't have the time to start training cooperation at this point.
Ezra was set with the martial arts club and others as well, from both the martial arts academy and the mage academy.
He was also selected as the leader because, out of all of them, he was the best academically and all around, and he also had valuable contributions to his name.
Since this was now an army setting, he was also given full authority over the group as their leader, and only others above him could override his orders.