Final Answer:
In Act IV of Cyrano de Bergerac, de Guiche decides to leave the regiment.
Step-by-step explanation:
As the plot unfolds in Act IV of Cyrano de Bergerac, de Guiche, initially portrayed as a self-serving and scheming character, undergoes a transformation.
In this act, he makes a pivotal decision to leave the regiment. De Guiche's choice is influenced by a shift in his priorities and values. He is moved by the sacrifices and bravery of the soldiers, especially Cyrano, and decides to part ways with his past self-centeredness. This decision marks a turning point in de Guiche's character arc, revealing a more honorable and compassionate side to his personality.
The departure from the regiment signifies his commitment to change and aligns with the themes of honor and integrity explored in the play.