How does Act I introduce the theme of Arms and the Man?
The main theme of Arms and the Man by George Bernard Shaw is the difference between the romantic view of war as a space for heroic individualism and a more realistic, strategic, and pragmatic viewpoint, in which the goal is not grand gestures but securing territory and managing logistics. In Arms and the Man, these two viewpoints are represented by two male characters, Major Sergius Saranoff, who represents the romantic upper class Bulgarian viewpoint and Captain Bluntschli, the Swiss mercenary, who represents the pragmatic viewpoint. Over the course of the play, Raina Petkoff's transference of her love from Sergius to her "chocolate cream soldier" represents a maturation in her point of view from romantic to realistic.
The first act introduces this theme in the conversations between Raina and Captain Bluntschli, where the experienced mercenary disabuses the idealistic young woman of her false and romantic notions about how battles are actually conducted.