Irony

Sergius' Victory

Sergius' victory is revealed to be the product of dumb luck rather than skill or bravery. The opposing army's ammunitions were depleted because of a mix-up in cartridge supplies. While he did display bravery, he learns that the grand gestures do not amount to success in battle. Being a soldier, he learns,

...is the coward's art of attacking mercilessly when you are strong, and keeping out of harm's way when you are weak. That is the whole secret of successful fighting. Get your enemy at a disadvantage; and never, on any account, fight him on equal terms (29).

War is a profession, a trade, and not a stage for romantic flourishes (as Bluntschli says). Sergius' success is only the result of someone else's failure.

Sergius and Raina

Sergius and Raina are, on the surface, made for one another. They are from the two richest families in Bulgaria, one is an elegant lady and the other a war hero. They refer to each other as "king" and "queen". However, under this surface lies two people who are going through the motions and putting on a performance of love. Sergius, the "brave" soldier, lacks the gumption to declare his love for the housemaid. He may lead a cavalry charge, but does not dare to marry below his station. Raina's idea of love is theatrical and exaggerated, based more on the idea than the man. The irony is that both characters are more suited to their impossible mates - Louka and Bluntschli. By the end of the play, the correct pairs are together, and all pretenses are dropped.

The Anecdote about the Swiss

Mistaken or hidden identity factors heavily in Arms and the Man. When Bluntschli arrives, Sergius and the Major have no idea that he is the escaped fugitive whose story has become a legend. They recognize him as a man who was both part of the opposing side and now a potential advisor. Though Catherine and Raina try to shoo him away, Major Petkoff implores Bluntschli to stay. The competing forces in the Petkoff house sets the stage for the farcical elements of the play, and also the ultimate breakdown of pretensions by Raina and Sergius.