I just had yet another realization. Traditionally, King Arthur's death is said to be 542 AD. Interestingly, in history, around that same time, the Plague of Justinian occurred a year prior (in 541 AD). This possibly means that King Arthur and his army, as they march towards Rome, must also deal with a plague that is occurring in the local area.
So, when we add the Plague of Justinian as yet another event that King Arthur must deal with (besides Mordred's betrayal), then that makes things even more terrifying and devastating in the narrative.

















