The decision of the tribunal is as expected - the men are declared guilty, and sentenced to be shot at dawn (7 o'clock). In their dark prison cell, the three convicted prisoners talk about their fate, as they are served their last meal on an immense tray. The repast is a duck dinner "compliments of General Mireau" but without utensils - they have been forbidden knives and forks. They are unable to eat their last dinner anyway. Ferol thinks of escape. Arnaud puts his faith in Colonel Dax, possibly for a last-minute reprieve. Paris wonders if they have friends among the guards.

Corporal Paris spots a cockroach:

See that cockroach? Tomorrow morning we'll be dead and it'll be alive. It will have more contact with my wife and child than I will. I'll be nothing, and it'll be alive.

Ferol crushes the cockroach and adds:

Now you've got the edge on him.

A door slams and a priest (Emile Meyer) enters and helps the men prepare themselves for their death sentence, comforting them: "Have faith in your Creator - Death comes to us all." Uncontrollably, Ferol weeps and whines in the face of death, and Paris gives the priest a letter for his wife, and begins to give his confession. However, Arnaud - an athiest, who has been drinking, criticizes the sanctimonious priest: "That's really deep! Death comes to us all." Holding up his whiskey bottle, he combatively declares: "This is my religion," and struggles with the priest and the others.

To subdue him after he has attacked the priest, Paris punches Arnaud, striking his head on the wall and sending him to the stone floor unconscious with a fractured skull. The doctor examines Arnaud, explaining that with his serious injury, he may not live through the night or may be unconscious the next day. He suggests that he should be pinched awake during the execution - "the general wants him to be conscious."

Dax summons Lieutenant Roget to his quarters and orders the reluctant officer the assignment of supervising the firing squad - a job which requires putting a bullet in each prisoner's head afterwards: "...You've got the job. It's all yours." Only hours before the scheduled execution, Dax is awakened and given information by Captain Rousseau, the artillery officer during the attack who was ordered by Mireau to fire on the retreating French. The additional material may have some bearing on the court-martial.

The film cuts to the chateau and the ballroom where the court-martial case was held. A dress officers' ball is in progress that evening with light chamber music playing. Dax asks to see General Broulard to report the new information he has just learned. The general leaves the ball to meet with Dax in the book-lined library. Broulard concedes that the records of casualties show that Dax's men did prove themselves. Dax asks how the men can be executed if that is true. Broulard replies that the execution will still proceed, with beneficial results:

Maybe the attack against the Ant Hill was impossible. Perhaps it was an error of judgment on our part. On the other hand, if your men had been a little more daring, you might have taken it. Who knows? Why should we have to bear more criticism and failure than we have to?...These executions will be a perfect tonic for the entire division. There are few things more fundamentally encouraging and stimulating than seeing someone else die...You see, Colonel, troops are like children. Just as a child wants his father to be firm, troops crave discipline. And one way to maintain discipline is to shoot a man now and then.

Dax will not let the comments drop - he is shocked at what he has heard. Opening the door, General Broulard attempts to return to the party. Dax mentions that he has irrefutable proof - in the form of sworn statements by the men who witnessed General Mireau ordering his own battery commander to shell his own position during the attack. The door slams shut upon his hearing of the faux pas. General Broulard remains inside and asks: "What has all this got to do with the charge against the condemned prisoners?" Dax implies that the execution would not proceed if all the pressure groups knew Mireau's actions to fire on his own men:

What would your, er, newspapers and your politicians do with that?...you are in a difficult position. Too much has happened. Someone's got to be hurt. The only question is who. General Mireau's assault on the Ant Hill failed. His order to fire on his own troops was refused. But his attempt to murder three innocent men to protect his own reputation will be prevented by the General's staff.

Broulard accuses Dax of blackmail, but then excuses himself, explaining how he has been rude to his guests too long. Unresponsive, Broulard does not indicate what he will do - will he pardon the men and mercifully stay their execution in time?

In the next scene, the morning of the execution is signaled by the crowing of a rooster. Regimented ranks of guard soldiers approach and enter the prisoners' room. Arnaud is strapped unconscious on a stretcher, Ferol continues to pray and kneel with a priest, and Paris is soberly silent and looks stoically resigned to his fate. As they are preparing to be escorted to their place of execution, Paris is offered a final drink. He remarks: "I haven't had one sexual thought since the court-martial. It's pretty extraordinary, isn't it?" And then he bursts into tears, breaking down and pleading for his life. He is encouraged by the rigid sergeant to pull himself together and not reveal his cowardice:

There will be a lot of dignitaries, newspapermen out there. You've got a wife and family. How do you want to be remembered?...Many of us will be joining you before this war is over.

Paris simply replies: "I don't want to die."

Troops are assembled before the chateau, with officers in full dress uniforms. In the tense, 7-minute firing squad scene, drums monotonously sound in the background as the prisoners are marched between lines of soldiers to the open area near the chateau, where three stakes are set up. The upright execution stakes grow larger and larger as the men and the camera approach. (Arnaud is carried unconscious and tied on a stretcher.) Inconsolable, Ferol whines, sobs, moans, clutches his rosary, and hangs on to the priest, asking: "What do I have to die for, Father?...I'm scared, I'm scared." The men are tied to the stakes, and Lieutenant Roget offers them blindfolds. Caskets wait in an open cart to the side. The words of the indictment and official execution are nervously read by Major Saint-Auban. Generals Broulard and Mireau stand nearby, as do other dignitaries to witness the final judgment. The firing squad raises its weapons (the ominous drum roll stops), readies, aims (with the commands: "Ready, Aim") - birds twitter - and then fires at the command to "Fire" - filmed subjectively from behind the firing squad. The victims momentarily twitch and then collapse dead.

The film makes a quick cut to a high-angle view of the High Command breakfast table of Mireau and Broulard, where they eat croissants and exult in the dignified sacrifice - and ironically discuss 'bad taste'!:

Mireau: I'm awfully glad you could be there, George. This sort of thing is always rather grim but this one had a kind of splendor to it, don't you think?
Broulard: I have never seen an affair of this sort handled any better.
Mireau: The men died wonderfully! There's always that chance that one of them will do something that will leave everyone with a bad taste. This time, you couldn't ask for better.

Dax joins their company, and is congratulated by the manner in which his men died. Then suddenly, Broulard - the dissimulating instigator of the entire travesty - remarks offhandedly to Mireau that he knows of his order to fire on his own men during the Ant Hill attack. He indicates that it was Dax who informed him. He knows that he is setting up Mireau to be the disgraced scapegoat for the entire affair - the fourth execution. Broulard informs him cheerfully and smoothly that he must submit to an inquiry for his incompetence: "There'll have to be an inquiry."

After being exposed, Mireau is enraged at him before striding out: "You're making me the goat. The only completely innocent man in this whole affair. I have only one last thing to say to you, George. The man you stabbed in the back is a soldier." Defeated and lacking honor, Mireau exits from their presence.

Turning to Dax, Broulard smiles, shrugs and sighs: "Well, it had to be done. France cannot afford to have fools guiding her military destiny." He then smiles and offers Dax, with congratulations, General Mireau's vacated command. After all, he has cynically assumed that Dax had selfishly wanted the promotion from the start:

Come, come, Colonel Dax. Don't overdo the surprise. You've been after the job from the start. We all know that, my boy.

But Broulard has mistaken Dax's integrity. Infuriated and in contempt, Dax replies that he has seen through the politicking and is not interested in furthering his own fortunes: "I may be many things, sir. But I am not your boy." The corrupt general is hurt: "It would be a pity to lose your promotion before you get it - a promotion you have so very carefully planned for." Dax refuses the promotion, telling him what he can do with it. This forces Broulard to command Dax to apologize: "Colonel Dax, you will apologize at once or you shall be placed under arrest!" Dax then apologizes, but berates him for his moral degeneracy:

I apologize for not being entirely honest with you. I apologize for not revealing my true feelings. I apologize, sir, for not telling you sooner that you're a degenerate, sadistic old man. AND YOU CAN GO TO HELL BEFORE I APOLOGIZE TO YOU NOW OR EVER AGAIN.

The general realizes he has misjudged and misinterpreted Dax, who has shown real humanity for his soldiers. Broulard cooly explains his reasoning for the soldiers' execution and for Mireau's inquiry:

Colonel Dax, you're a disappointment to me. You've spoiled the keenness of your mind by wallowing in sentimentality. You really did want to save those men, and you were not angling for Mireau's command. You are an idealist - and I pity you as I would the village idiot. We're fighting a war, Dax, a war that we've got to win. Those men didn't fight, so they were shot. You bring charges against General Mireau, so I insist that he answer them.

And then he innocently appeals: "Wherein have I done wrong?" Dax gasps and replies bluntly and quietly: "Because you don't know the answer to that question, I pity you." Dax walks back to his post alone.

In the final memorable sequence of the film, Dax wanders in the streets of the town towards his quarters. He hears lecherous, cat-call whistling and shouting in a nearby tavern, where men from his troops are getting drunk for "a little diversion" (according to the master of ceremonies tavern keeper) following the execution. He stands outside in the doorway, witnessing the coaxing of a frightened, fragile, teary-eyed and innocent German blonde girl (Susanne Christian in the credits, actually Christiane Harlan, director Kubrick's future third and last wife). She may be a prisoner, or a refugee who is forced to sing a song in front of rowdy soldiers who are cat-calling, hooting, and laughing at her.

The girl is introduced by the tavern keeper as "our latest acquisition from the enemy...from Germany, the land of the Hun!" She is "a little pearl washed ashore by the tide of war" who has "a little natural talent" (he gestures over her physical curves) and "she can sing like a bird - she has a throat of gold." Dax recognizes companions of the executed men and is disappointed by their apparent lustful callousness shortly following the death of their own comrades. In front of the raucous troops, the timid and fragile young girl - with tears on her cheeks - begins to sing a ballad - in German. [It is a universally-known folk song of love in war, called "The Faithful Soldier" - (La Treue Hussar (Fr.) or Der treue Hussar (Ger.)).] It is a simple, sweet song that is inaudible until the audience quiets down and listens intently and respectfully to her plaintive voice. Soon, hers is the only voice in the tavern:

(loosely translated, in part)

A faithful soldier, without fear,
He loved his girl for one whole year,
For one whole year and longer yet,
His love for her, he'd ne'er forget.

This youth to foreign land did roam,
While his true love, fell ill at home.
Sick unto death, she no one heard.
Three days and nights she spoke no word.

And when the youth received the news,
That his dear love, her life may lose,
He left his place and all he had,
To see his love, went this young lad...

He took her in his arms to hold,
She was not warm, forever cold.
Oh quick, oh quick, bring light to me,
Else my love dies, no one will see...

Pallbearers we need two times three,
Six farmhands they are so heavy.
It must be six of soldiers brave,
To carry my love to her grave.

A long black coat, I must now wear.
A sorrow great, is what I bear.
A sorrow great and so much more,
My grief it will end nevermore.

The soldiers - for once affected and showing some regard for human life - join her and hum along with their faces drawn to her. The human feelings in the song transcend the language barriers - some of the French soldiers may know the tune of their enemy's song, and some may even know the words. One of the youngest recruits in the audience has tears flowing down his cheeks. The song evokes memories of their youth, their homes, and their loves in a world they may never see again. There is still a hint of their common humanity and sensitivity in the men despite the misery and depravity of war.

Suddenly, Dax, who has been watching and listening impassively, receives a message from another officer with orders to return his unit immediately to the front's trenches - little has changed in the war. Still in charge, Broulard has transferred Dax and his men back to the front. To give his men the "short" rest they were promised but never fully received following the assault on Ant Hill, Dax replies, with the film's last line:

Well, give the men a few minutes more, Sergeant.

The sound of drums and military music playing the "Soldier Boy" song rise in volume and drown out the sound of the folk song, as Dax returns to his quarters down the street.