Final answer:
Act IV of 'Cyrano de Bergerac' is set during the siege of Arras, focusing on the experiences of Cyrano, Christian, and the Gascony Guards.
Step-by-step explanation:
Act IV of Cyrano de Bergerac takes place at the siege of Arras, where the French are battling the Spanish. It is set in a encampment where the Gascony Guards, including Cyrano and Christian, are stationed.
This setting contrasts starkly with the lively and sophisticated environments of Paris, such as the literary salons and theaters that were central to the cultural life during the French Enlightenment.
The harsh realities of war and the soldiers' yearning for love and communication are highlighted in this act.