In the following scene from Act 2, Sergius and Major Petkoff discuss the battle retrospectively, during which they recall the fact that Bluntschli was harbored by two Bulgarian women. This scene introduces dramatic irony to the Act, on account of the fact that the two men are unaware of Raina and Catherine's involvement in Bluntschli's escape:
PETKOFF: (grinning). Sergius: tell Catherine that queer story his friend told us about him—how he escaped after Slivnitza. You remember?—about his being hid by two women.
SERGIUS: (with bitter irony). Oh, yes, quite a romance. He was serving in the very battery I so unprofessionally charged. Being a thorough soldier, he ran away like the rest of them, with our cavalry at his heels. To escape their attentions, he had the good taste to take refuge in the chamber of some patriotic young Bulgarian lady.
This scene complements an earlier scene in Act 1, during which Bluntschli reflects on the battle and describes Sergius's initial charge as foolhardy and ridiculous, undermining Raina's construction of him as the ideal romantic hero. While Bluntschli criticizes the naïveté of Sergius's romantic, antiquated wartime principles, Sergius criticizes Bluntschli's taste, implying that he fought without honor or decorum. The use of dramatic irony in this passage functions as a device to allow readers knowledge of where both men stand ideologically.
In the following scene from Act 2, Sergius discusses the traditions and principles of warfare. This quotation serves as a prime example of situational irony, highlighting the contradictions inherent to a formalized system of rules for engaging in military conflict:
SERGIUS: I won the battle the wrong way when our worthy Russian generals were losing it the right way. That upset their plans, and wounded their self-esteem. Two of their colonels got their regiments driven back on the correct principles of scientific warfare. Two major-generals got killed strictly according to military etiquette.
Both the phrase "correct principles of scientific warfare" and the following phrase "military etiquette" imply, rather strangely, that there is something principled or dignified in an act of mass slaughter. To speak about war in such a way implies a certain level of remove from the inherent chaos and mayhem of the battlefield, as well as the terror inflicted on civilians in due course during military campaigns. Generals and captains may calculate their moves in a "scientific" manner according to commonly-held rules of engagement; but these social niceties of war produce results that couldn't possibly stray further from the principles of kind and considerate treatment.
Regardless of the rationale behind the fighting, then, war is never "proper"—it is always violent and dehumanizing.