Dawn is breaking. The soldiers awake to another day of war. They no longer know the reason for the fighting. War has become a habit – for thirty years. An Italian messenger, having made his way through enemy lines, arrived in the night with a letter from the Emperor to the Commandant. In his fatigue he sings a song of peace, women and flowers which evokes astonishment from the soldiers. These are forgotten joys.

Suddenly cries for bread are heard from outside: civilians in an uproar are reported to be breaking down the fortress gate. The Bishop, the Mayor and other deputies enter to beg the Commandant to surrender to the enemy – but he refuses to capitulate. For him surrender means dishonor. For him there is only victory or death.

A front line officer announces that the ammunition is finished, that their situation is hopeless. The Commandant reads aloud the letter from the Emperor which orders him never to surrender. But when the deputies point out the hopeless suffering of the people, the Commandant’s expression changes and they leave in the hope that there will be a change.

The Commandant now reveals his plans to his soldiers. He intends to use the left-over ammunition in the cellar to blow up the fortress. The soldiers are given the choice to share his fate. Most of them choose to stay and they prepare for the explosion.

Maria comes to look for her husband. The bright sunshine and the smiling faces of the people have filled her with hope for the future. She wants to regain her husband’s love. He orders her to escape: within an hour the town will have fallen to the enemy. She refuses to leave him; she would rather share his death.

The soldiers return, prepared to die. Everything is readied for the explosion and the Commandant gives the signal. A cannon shot is heard. The Commandant believes the enemy is attacking and he countermands his order in the hope of dying honorably in battle. The cannon shots are followed by church bells. The deputies announce that war is over. The enemy arrives to make peace, but the Commandant cannot accept it and violently lays hold on his sword. Maria interposes and the sword falls. In her eyes he reads love. He gradually succumbs and greets his enemies as fellowmen. People from both sides praise the peace, the sun, and the new life.