Oran is quickly made parallel to a war zone after the outbreak of the plague. The mass graves, the militaristic occupation of Oran, and even the "deratization" vehicle that rattles through the town like a machine gun all contribute to the feeling that Oran is at war. Indeed, the narrator often points out that war and pestilence are both uncontrollable, unpredictable aspects of the human condition that bring senseless suffering.
Whether Camus is purposefully creating an allegory about French resistance to the Nazis during WWII (which many believe is true), or whether he is trying to make a more general point, he is nonetheless drawing a parallel between the human suffering imposed by other humans and human suffering that comes from pestilence; both, he says, have the same devastating effects. Rieux’s comment – that we allow suffering to occur because we can not comprehend its magnitude – can definitely be applied to the atrocities of war (in fact, Rieux himself directly compares the two in his famous standing-by-the-window scene).