If it requires conventional flight to return, even with the current technological level of the Red Blade Army, it would take at least one hundred and twenty years, and considering the battle time, the return journey for the Vanguard Army could take over two hundred years.
Two hundred years is enough time for the Red Blade Clan to rapidly propagate and expand its population again, and to form an even larger, new fleet.
Ren Zhong initially thought that by voluntarily undertaking the heaviest combat tasks, Jin Shi would immediately agree.
