The Marquise has arranged a marriage between Marie and the Duke of Krakenthorp. At the Marquise's castle, Sulpice is recovering from an injury. He is supposed to be helping the Marquise with her plans. The Marquise gives Marie a singing lesson. Marie slips in phrases of the regimental song with Sulpice's encouragemment. The Marquise loses her temper (Trio: ""Le jour naissait dans la bocage"").