One night in January 1636, the wagon stands near a farmhouse outside the Protestant town of Halle. Out of the woods come a Catholic Lieutenant and three soldiers in full armor. They have come from a guide to the town and the Lieutenant orders to kill anyone who makes a sound.
They knock and seize the Old Peasant Woman who answers. The soldiers bring out an Old Peasant and his son. Kattrin appears on the wagon and her mother has gone to town to buy supplies because the shopkeepers are fleeing and selling cheap. The soldiers demand a guide; the son refuses, even upon the threat of death. The soldiers then threaten to destroy their cattle. The son complies and exits with the soldiers.
The Old Peasant climbs on the roof and spies a Catholic regiment, which has killed the watchman and readies for a surprise attack on the town. Convinced there is nothing they can do, the Peasant Woman begins to pray, asking God to protect their family members in the town.
When she learns of the Peasant Woman's grandchildren in town, Kattrin quietly climbs on the roof. She withdraws a drum from under her apron and begins to beat it. The peasants command her to stop, threatening to stone her. The soldiers return, threatening to kill them all. Craftily, the First Soldier promises Kattrin that they will spare her mother if she stops and accompanies them to town. She ignores them, as the young man notes, and she does not beat for her mother alone. The Old Peasant begins maniacally chopping wood to conceal her drumming with an innocent peacetime noise. The soldiers consider setting the farm on fire.
Kattrin listens and laughs. Enraged, the Lieutenant orders his men to bring a musket. The Peasant Woman suggests that they smash the wagon. The Young Peasant deal it a few blows; Kattrin pauses in distress but continues. Suddenly he cheers her on and the soldier beats him with his pike. The second soldier returns and shoots the weeping Kattrin. Her final drum-beats mingle with the thunder of a cannon. She has saved the town.
Toward morning, Mother Courage sits by Kattrin's body in front of the wagon. The drums and pipes of the marching troops are heard. The peasants order the parasite away and Courage must follow her regiment. Courage responds that Kattrin has perhaps fallen asleep and sings her a lullaby. The peasants bring her to her senses. Courage fetches a sheet from the wagon to cover the body. She plans to go to Eilif. The peasants offer to bury her. Courage pays them and harnesses herself to the wagon. She is confident she can manage: "I must get back into business" she resolves. As she calls to the passing regiment, the soldiers sing her signature song.