It's 1916 near Pall Mall, at Three Forks of the Wolf, in Tennessee. At the local church, Pastor Rosier Pile (Walter Brennan) is delivering his sermon. There's a disturbance outside. Alvin C. York (Gary Cooper), Ike Botkin (Ward Bond), and Buck Lipscomb (Noah Beery Jr.) are riding their horses, whooping and hollering, and shooting. They were drunk. York shoots his initials into a nearby tree.
Next day, there's a sign on a building that says, "Rosier Pile, General Merchandise." It's Pastor Pile's business. Inside, a traveling salesman is attempting to interest Pile in buying some hats and bloomers. The pastor says the women around there would not be interested.
One man at the store has a copy of the Tennessean Dispatch newspaper, but the men aren't interested in the headline, which is about the Germans on the attack in Europe.
The men at the store recall many times past when Alvin York and his drinking got him in trouble. Mrs. York comes into the store and they all fall quiet. She seems to have mixed feelings about her son. She tells Pile how Alvin works very hard, for very little reward, and she doesn't blame him for cutting loose now and then, however she considers that perhaps some old fashioned religion might do him some good. Pastor Pile promises to go have a talk with him.
Mrs. York sends Alvin's younger brother, George (Dickie Moore), to go find Alvin, who reportedly traveled up near the Kentucky border with his buddies.
George finds Alvin at a bar that sits exactly on the boundary line between Kentucky and Tennessee. Selling booze is only legal in Kentucky, so the bartended has to be sure and sell it only on that side of the room.
George goes into the bar, rifle at the ready, and tells Alvin their mother wants him. Alvin always does as his mother says, so he gets up to go. A man laughs at him, teasing him for running off to his mother. A fight ensues and continues until George reminds Alvin that their mother is waiting.
On an ensuing day, the pastor rides his horse, Fred, to see Alvin, who's plowing furrows on a rocky ridge. The pastor tries to convince Alvin to try and shake loose of Satan before he gets done in. Alvin doesn't disagree with the advice, but he doesn't know exactly how to go about doing that. The past makes an analogy with a nearby large oak tree, noting that there are strong invisible roots that anchor the tree to the earth. Alvin's not opposed to religion, he just thinks it has to come to him and not be pursued.
Another day, Alvin, George and three of their hounds are chasing a fox. They run through the yard of a nearby farm and Alvin gets distracted by Gracie Williams (Joan Leslie), out sitting on her porch. He stops to say hello. He knew Gracie, but hadn't seen her for a long time and she'd grown up considerably.
At home that night, when Alvin asks his mother some questions about "settin' up" in life (i.e., getting married), she asks who the girl is. He tells her it's Gracie Williams. Mother just shakes her head, perhaps thinking that Alvin isn't ready for marriage.
Zeb Andrews (Robert Porterfield) is over to see Gracie and ask her to the shindig Saturday night. They are out on the front porch when Alvin comes walking up. When Zeb realizes that Alvin has come by to court Gracie, he starts making subtly snide remarks about Alvin. When Gracie goes to get them something to drink, Alvin grabs Zeb and jerks him off the porch. When Gracie returns, she sees walking away off in the distance and she's upset at Alvin for being the cause.
Alvin tells Gracie he wants to marry her. Attracted to him, but upset at his behavior, she tells him she wouldn't have him on a Christmas tree. Alvin incorrectly determines she said that because Zeb has a piece of prime farming bottomland. He tells Gracie that he could get some bottomland too, and he determines to go make that happen.
York stops by some bottomland and scoops up a handful, taking it home to show his mother. She tells Alvin that the bottomland folks have always looked down on them, and always would. She told him that her father had worked long and hard to get him some bottomland, but he finally had to give it up. York is determined that he won't be stopped.
Alvin to see a man named Thompkins, who has a piece of bottomland for sale. He takes everything he can spare to barter with, including some fox pelts, chickens, his mule, a broken clock, and some goose feathers. Thompkins offers him $50 for all of it, even though it's probably worth another $15-$20. Thompkins wants $120 for the bottomland that he has for sale. Alvin says ok, and Thompkins gives him 60 days to come up with the $70 balance.
York sets about taking on physically demanding jobs for others, including removing big rocks from a man's land for 75 cents/day. George helps him splits rails and pull stumps, using their horse. York sells a fox pelt to the pastor.
Miss Gracie goes out to see York one day while he's plowing a field. She wants to say something to her, but can't find the words, so he grabs and kisses her. She tells him that's what she wanted, and she runs off.
York has accumulated only $44.35 as the 60 day deadline approaches. As he lays down to sleep, exhausted, his mother pulls a blanket over him and prays to the Lord to help him.
Alvin goes to see Mr. Thompkins, asking for an extra four days. He knows that there is a beef and turkey target shoot coming up and if he can win those shoots and sell the turkey and the beef, he'll have the money. Thompkins claims that another man wants the land, but he decides to give Alvin the extra four days.
The day of the shoot, Alvin gets a turkey, when others failed, by tricking the bird with a gobble-gobble imitation, resulting in the turkey popping it's head up from behind a log, then Alvin shoots it. He trades the turkey to the contest organizer for an additional shot at the beef prize.
For the beef shoot, each contestant must buy a shot. Alvin buys four more, in addition to the one he traded the turkey for. He wants to win the top five prizes, which would comprise the entire steer. Surprised, none of the other contestants believe Alvin has a chance. "Ain't nobody ever cut five centers, lessen he was Daniel Boone, an' you ain't wearin' no coon-skin cap!" one of the other men tells him.
The target is a white-colored V shape cutout. The shooters aim at the center notch of the V. Alvin cuts his first four centers. The last man with a chance to win the last fifth of the steer, Tom, cuts center with his last shot. Alvin then wets his front site, aims and fires. He cuts center also. Pastor Pile is the judge, and declares the shots were no more than a hair apart, "but Alvin done cut center fair and square!" and Alvin was declared the winner.
Alvin then puts the cow up for a drawing, selling chances as a way to make the money he needs. He collects what he needs and approaches Mr. Thompkins, who was just then arriving with Zeb Andrews.
Thompkins tells Alvin that he decided to sell the bottomland to Zeb. "Your time was rightly up," Alvin is told, "and besides, I never thought you had a chance to win that contest anyhow." Alvin is aghast, ready to punch Thompkins and/or Zeb. They both turn around and put some distance between themselves and Alvin, as Alvin's friends and the pastor hold him back.
Alvin can't believe Thompkins went back on his word. He dwells on it into the night, and as he drinks with his buddies, he decides things must be set right, so he takes off to go get what's rightfully his. He heads for the Thompkins place, riding in a thunderstorm, with lightning flashing very close by. There's a flash and he wakes up to find his mule on the ground, but alive, and his rifle barrel split. He's not hurt, but when he realizes they'd been struck by lightning, he takes that as the sign from above he thought would come if he was meant to have religion.
York rides over to the church and walks inside as services are underway. The pastor sees him and calls for the congregation to sing, "Give Me That Old Time Religion." York makes his way forward, taking a knee and shaking hands with the pastor.
Sometime later, Alvin goes to see Thompkins, who thinks Alvin means him harm and grabs a wrench to protect himself. Alvin tells him he just wants to buy his mule, Abraham, back. He also asks forgiveness for getting upset with Thompkins earlier. Thompkins decides to offer Abraham to York for just $20, and he throws in the clock, which doesn't work anyway.
York next goes to see Zeb, who hides, but York is there just to ask him about a possible job working that bottomland Zeb bought from Thompkins. Thompkins admits that he bought the land just to spite York, and offers to let him till the land on a share-crop basis, and maybe within a few years, York could afford to buy it. York is pretty well convinced now that living in accord with the words of the Bible is well substantiated.
Finally, Alvin goes to see Gracie and apologize for coming between her and Zeb, the way that he did. Of course, that's not what she wanted to hear and she gets mad at him for that too, telling him she wants him, not Zeb, not any bottomland and not a beef cow. She runs off crying, leaving Alvin totally mystified.
A man named Luke comes riding into town to announce that President Wilson had declared war against Germany. All able bodied men were required to register with the draft. Some men didn't want to wait to be drafted and intended to enlist right away, but when some asked Alvin what he was going to do, he said "wait." In fact, the pastor knew that Alvin hadn't even registered, and he confronts him in private about it. York tells the pastor that he's not going to register, that "War is killin', an' killin' is agin' the Book." The pastor tells York that he needs to register or get in trouble. He advises Alvin that he could then request exemption from fighting, on the basis of religion. The pastor offers to write the letter to the draft board.
The pastor's letter to the draft board on behalf of York is rejected. The board determined that the pastor's little church was not one of those broadly recognized throughout the country. The pastor sets about preparing an appeal.
Meanwhile, Alvin shows Gracie where he plans to build their house on the bottomland, most likely within 2-3 years.
York's final appeal was denied by Washington, D.C. He is ordered to report to Nashville that next night. He tells the pastor he won't go, that he'll hide in the hills and fight them if they come after him. Alvin is told by Pastor Pile that "The war is clear across the ocean, and a lot can happen before you get there. Trust in the Lord Alvin." When Alvin realizes how his attitude and talk was not in accordance with what the Bible says, he decides he'll go.
It's a tough goodbye for York, as he faces his mother, brother and sister Rosie (June Lockhart). Alvin gives George his rifle. Gracie comes by the house and hugs him, cries, then quickly kisses him before rushing off. He tells her and his family, "I'll be a comin' back!"
York reports to Camp Gordon, Georgia. The officers and non-coms are advised that York is a conscientious objector, so he should be watched closely. It's apparent that such men are not held in high regard by the non-comms, suspicious that it's just an excuse used by cowards.
Alvin asks one of the other soldiers, a man from New York named Pusher Ross (George Tobias) about a subway, which he'd never heard of.
York is assigned rifle #218102. The Sgt. sarcastically cautions him not to kill anyone with it before he gets to France. The first day on the firing line, York hits low and right on the center ring, then figures out that the rifle sights aren't quite right, and puts the next five in the bull's eye. When an officer asked him where he learned to shoot, he said he just always seemed to know how.
Alvin is ordered to report to a Major Buxton (Stanley Ridges). There is also a Captain Danforth (Harvey Stephens) in the room. York is told that Captain Danforth is prepared to recommend him for promotion to corporal and assignment as a shooting instructor. York tells them that he is against the promotion, and against killing, or facilitating the killing of other men. Danforth engages York in a debate about Biblical verses and their meanings. York proves to be well versed, and his beliefs are confirmed.
The major hands York a copy of the History of the U.S. and tells him the book is full of stories about great men. He tells York about the concept of freedom, including it's importance to men like Daniel Boone, who was a very well known figure to York. The major goes on to explain that the preservation of freedom sometimes requires the full measure of devotion, which is a man's life. Major Buxton allows York to take a 10 day leave of absence, to go home and think about his feelings and beliefs. He asks to take the history book with him and the major tells him to go ahead.
Back in Tennessee, Alvin takes one of his hunting dogs, the U.S. history book, and the Bible, and sits on a rock ledge, reading and thinking in solitude about his options. He is confused about whether country or God comes first in a man's life. When he reads the words attributed to Jesus: "Render unto Caesar the things that are Caesar's, and unto God the things that are God's," that helps him decide. He returns to Georgia and tells Major Buxton he had decided to stay in the Army, even though there were many things he hadn't fully figured out yet.
York is promoted and once he and his All-American Division completes their training, they sail for France. York writes home and tells his family and Gracie that they will soon be moving up to the front lines.
Once they move to the front, they are hunkered down in a trench, discussing things with a couple of Brits. The Brits are teaching the Americans how to interpret the sound of incoming artillery as to whether they need to duck or not, when an American named Bert Thomas (David Bruce) takes a piece of shrapnel through his helmet and dies.
York and his division were part of the Meuse-Argonne Offensive, also known as the Battle of the Argonne Forest, a part of the final Allied offensive of World War I that stretched along the entire Western Front.
On 8 October, 1918, orders were given to exit the trenches and attack the Germans at 0610. The Americans do as ordered, experiencing heavy fire and casualties. The first action for York was to enter a German trench as part of an ambush of some approaching Germans. As the sides engage, some of the Germans turn around to go back and warn their troops to the rear. York pulls a grenade and lobs it in front of the Germans, halting their escape.
York and few men from his division take some prisoners. As they proceed to try and find their way back to the American's line, they are ambushed by a German machine gun. The senior non-comms are injured too badly to continue, so Sergeant Bernard Early orders York to take over. York immediately takes off around a side hill and takes out two machine guns that had the men pinned down. He proves just as good with a handgun as with his rifle. His fire is so deadly and efficient, that dozens of Germans surrender, not realizing it's just one man attacking them.
One German decides to pull the pin on a grenade he had and he throws it, killing Pusher. York goes to find the man who threw it and when the man runs, York shoots him. He tells the German officer to order his men to drop their utility belts and not to try anything like that again. There's only seven U.S. soldiers with York, controlling maybe 50-75 Germans.
They march on through the trench with their prisoners, coming upon some more fighting. York tells the German officer to order the men who are shooting to surrender. The officer orders his bugler to sound retreat, adding to the Americans prisoner total.
York tries twice to turn the prisoners over to the first Americans they come across, but they don't know what to do with them, so he continues on to a town were there are already other prisoners imprisoned. The officer in charge is shocked to see that just eight men had captured 132 Germans, and he helps find somewhere to put them.
Rumors start flying around the American infantry forces, and before too long, the stories have been exaggerated to the point that York supposedly single-handedly captured the German Kaiser, plus half the German Army.
Later, at the site of the battle, York was describing his actions and when he was asked by a general how many men he'd killed, he said he didn't know. Danforth was there and said they had counted 20 German bodies.
York explains to the then "Colonel" Buxton that he was still set against killing other men, but when he saw the German machine guns killing so many Americans, he had to do it to save lives.
Sergeant York was awarded the Distinguished Service Cross, Medal of Honor, the French Croix de Guerre, the French Legion of Honor, the Italian Croce di Guerra al Merito, and the Montenegro French War Medal.
Tennessee Congressman, Cordell Hull (Charles Trowbridge), was on the dock to meet York as he disembarks from his ship back in the U.S. There's a ticker tape parade. The mayor of NY hands him the key to the city. He asks only for a ride on the Bronx Express Subway.
Officials take him to a fancy suite and there's a framed photo of his mother on the piano, which he finds very touching. He gets a phone call. It's Mother York on the other end, but they have trouble hearing each other. He speaks with Gracie too.
York is recognized by Congress and the stock exchange suspends it's operations in his honor, but Alvin just wants to go home. Mr. Hull tells him there is a quarter of a million dollars in offers to do movies, theater and sponsorships. Alvin tells him he's not proud of what he did in France and doesn't want to profit from it. He chooses to go home.
In Crossville, TN, there's a large crowd at the train depot. York is told he's the biggest hero in those parts since Danl' Boone and Andy Jackson.
Alvin and Gracie go to check out their bottomland. Alvin is surprised to see that a new bridge had been built across the creek. They spoke about plans for the governor to marry them, but York is concerned that he doesn't have anything to offer Gracie yet, so he wants her to wait another 2-3 years. She tells him there's no need, then asks him to close his eyes as she leads him up the path. When he opens his eyes, he sees that the people of the State of Tenn. had built him a house, barn, and water pump, all located on 200 acres of prime bottomland. He seems amazed and happy as he and Gracie move forward hand-in-hand to check it out.