In 1810, as the defeated Spanish Army retreats before Napoleon’s advancing forces, they leave behind a massive artillery cannon. In order to keep the cannon away from the enemy, the soldiers push it over a ravine, where it languishes until British naval captain Anthony Trumbell arrives in Spain to claim it. The Spanish general with whom the British arranged to take possession of the cannon has fled, however, and only the Spanish guerrilleros, as the peasant guerrilla fighters are known, remain. Miguel, the group’s leader, informs the conservative Trumbell that he is the only authority left in town, and takes Trumbell to see the cannon, which is forty-two feet in length and weighs seven tons. Despite Trumbell’s prior claim on the gun, Miguel insists that first he will take it to his hometown of Avila to liberate the town from the French. Desperate, Trumbell agrees to help the guerrilleros raise the huge weapon from the ravine. Because Trumbell is the only one who knows how to fire the cannon, Miguel is forced to allow him to accompany them, despite his irritation at the Englishman’s imperiousness. Another source of contention between the two men is Miguel’s voluptuous mistress, Juana, to whom Trumbell is attracted. The 1,000 kilometer journey begins, with 200 peasants accompanying the guerrilleros to help move the huge gun. One evening, the group engages in a brief fiesta, during which Miguel grows jealous of Juana’s interest in Trumbell, although she asserts that she is free to do as she wishes. In Avila, French general Henri Jouvet orders that ten Spanish citizens be hanged every day until the location of the gun is revealed. Meanwhile, the guerrilleros’ arduous journey has continued until they reach a large river that must be crossed. Trumbell designs a raft and launch for the cannon, but halfway across, the guide ropes break and the gun is swept downstream into the rapids. After it crashes into some rocks, Trumbell inspects the weapon and although it is intact, he is infuriated that they will need at least two thousand people to free it from the mud. Miguel storms into a nearby bullfighting stadium, where the French soldiers are surrounded by his men. Miguel then chastises the Spanish audience for sitting with their occupiers, and dares those who still feel national pride to help him. After the gun is freed from the mire, the march continues until the guerrilleros come across a French camp. Although the French soldiers outnumber them, it would take an additional three weeks to circumvent the camp, which Miguel refuses to do, despite Trumbell’s pleas for reason. The two men argue and Trumbell declares that he wants no part of Miguel’s fatalistic insistence on attacking the camp. When Juana challenges Trumbell, however, stating that she knows he wants to act “more like a man than a cold piece of English mutton,” he joins the fight, leading a group of men who steal the French gunpowder. After their triumph, Trumbell is disgusted when Miguel orders the deaths of two captive French soldiers whom they are interrogating, and Miguel gruffly tells him to leave. Juana pleads with the Englishman, however, telling him that Miguel needs him. Juana explains that when she lived in Avila, Jouvet desired her and threatened to kill her father and brother if she did not submit to him. Although she complied, Jouvet killed her relatives anyway, after which she fled to the hills. There, she lived without purpose until she met Miguel, who has inspired hundreds of guerrilleros to follow him despite his stubbornness. Trumbell calls Juana cheap for remaining with Miguel when she does not love him, but then kisses her. After Juana reveals that she has already apologized to Miguel for him, Trumbell agrees to continue for her sake. At the next camp, the guerrilleros raid a village and take its food and supplies, despite the villagers’ pleas to be left some food. Infuriated by Trumbell’s subsequent interference, Miguel allows his second-in-command, Carlos, to challenge Trumbell to a knife fight. Juana tries to intervene but Miguel asserts that he will only allow Carlos to kill Trumbell “a little.” When Carlos goes after the Englishman with great ferocity, however, Trumbell defends himself and kills Carlos, much to his horror. After the guerrilleros then learn that a large company of French infantry is headed their way, Trumbell and Jose, a young fighter, volunteer to blow up the bridge over which the French must cross. Jose is killed during the dangerous assignment, although he and Trumbell succeed in blowing up the bridge and wiping out the entire company. Later that day, Juana succumbs to her passion for Trumbell, and after their rendezvous, he assures her that they will have a happy life together. When she returns to camp, Juana is gently confronted by Miguel, who states that he can only give her Avila, then leaves a pair of sandals that he made for her. In Avila, Jouvet is furious to learn about the loss of the company, although he now knows that the guerrilleros will have to traverse a narrow mountain pass. As Jouvet plans an ambush, Miguel and Trumbell attempt to placate the peasants who are refusing to accompany them through the pass. Without their help to pull the gun, the guerrilleros will be in jeopardy, but Miguel insists on continuing, and they begin their march with the wheels and mules’ hooves muffled to prevent revealing their location to the French. The enemy soon locates them, however, and begins firing. Hearing the shots, the reluctant peasants rally to the guerrilleros and succeed in pulling the gun to safety. Miguel avoids roadblocks by marching through the hills, but after the gun is pulled up one steep hill, Trumbell points out that it will gain weight going downhill and they will not be able to control it. Miguel again refuses to listen to the Englishman, and as a result, the gun goes careening out of control and is damaged. Needing a safe place to repair it, Miguel, Trumbell and Juana go to a nearby town, where Miguel pleads with the local bishop to allow them to hide the gun in the cathedral. The bishop loftily refuses until Trumbell reprimands him, reminding him how desperately the peasants are working to free Spain. Juana is touched by his words, as she believes that he has finally begun to appreciate their cause. The bishop agrees to let the guerrilleros use the cathedral, and the gun is repaired, then snuck out again during the Holy Week processions without attracting the attention of the watching French soldiers. Soon after, the group comes within sight of Avila, and the night before their attack, Trumbell explains to the ten thousand assembled peasants that although he will be able to breach a hole in the fortified walls with the cannon, at least half of them will be killed by the French guns before they can reach the city. Alone with Juana, Trumbell makes her promise that she will stay with him by the gun where she will be safe, then prepares the gun for the siege. As Juana walks through the camp, however, she changes her mind and tells Trumbell that she must fight alongside Miguel and her people, despite her love for him. The next morning, the siege of Avila begins, and with the huge cannon, Trumbell is able to blast a hole through the fortress walls. The guerrilleros and peasants then rush through the open fields, and although many of them are slaughtered, enough reach the wall to defeat the French and retake the town. Juana is struck down during the fight, and after the battle, Trumbell finds her as she lays dying. With her last breath, she declares her love for him, after which he finds Miguel’s body just outside the city wall. Determined to fulfill the brave peasant’s desire to reach the statue of Saint Teresa, Trumbell carries Miguel into Avila and lays him at the feet of the statue. The Englishman then departs Avila with a large contingent of peasants pulling the gun behind him.