Obviously speaking, the rank and file soldiers were the first to descend while the bigwigs were left at the back to watch how their peons worked. After all, one could say that the effort placed in the rank and file would show the calibre of the generals that were sitting at the backend.
The school of killer fishes were not the only enemies that the Rifle Mages had to contend with. A variety of animals were moving into the scene as the Dashavatara shattered the isolation barrier that Jin was so proud of keeping Ress in. This gave the Dashavatara's armies to work with unrestrained space although that did not matter for Ress and her people.
After all, it was pretty obvious that the Dashavatara were aiming at the people of Ress and not the other kingdoms. Even if they did, Ress was not at liberty to be concerned for the rest of their neighbours.