True story of the farm boy who made the transition from religious pacifist to World War I hero.

The Valley of the 3 Forks of the Wolf, located in the Cumberland Mountains in Tennessee, is the home of the Yorks, a family of poor mountain farmers. In the spring of 1916, a drunken Alvin C. York, the oldest son, interrupts a church service attended by his mother, sister Rosie and brother George, when he and two friends take potshots at a nearby tree. Later, at Mother York's request, Pastor Rossier Pile speaks to Alvin, but has little influence on the hell-raising young man. One day, while hunting, Alvin encounters Gracie Williams and instantly decides to marry her. When he tells this plan to Gracie, however, she turns him down cold. Convinced that Gracie's objections would be overcome if he had more money, Alvin determines to buy a rich piece of bottomland to farm. He works day and night to earn the money, collecting the final amount after winning a shooting contest, but when he brings the money to Nate Tompkins, the owner, he learns that Nate sold the land a few minutes earlier to Zeb Andrews, his rival for Gracie's hand. Alvin proceeds to get very drunk and then, on his way to kill Zeb, is hit by lightning. Taking this as a sign from God, Alvin starts to attend church and makes his peace with Zeb and Nate. Soon, a surprized Zeb offers to let Alvin sharecrop the land he just bought. When the United States enters World War I, Alvin refuses to register for the draft, believing that killing, even as a patriotic duty, is against the Bible. Pile convinces him to register as a conscientious objector, but Alvin's request for "C.O." status is denied and he is drafted. At Camp Gordon in Georgia, Alvin's shooting so impresses his superiors that they promote him to corporal and make him an instructor. Although he agrees to teach, Alvin turns down the promotion because of his religion. His superior officer, Major Buxton, counters by arguing the importance of defending freedom, and gives Alvin a furlough to think over the proposition. In the end, Alvin decides to accept the promotion, and later, his unit sails for France to fight in the Argonne offensive of 1918. As the men advance through an area surrounded by Germans, Alvin single-handedly kills twenty Germans and convinces 132 more to surrender. Together with the seven men remaining from his unit, Alvin brings the German prisoners back to headquarters. He is awarded a French medal, the Distinguished Service Cross and the Congressional Medal of Honor. After returning to a hero's welcome in New York, Alvin wants nothing more than to go back to Tennessee. He refuses all the money offered to him, explaining that he did what he did because he had to and is not proud of what happened. Back in Tennessee, Alvin is reunited with his family, his beloved mother, and Gracie. Despite Alvin's wish not to gain by his actions, the people of Tennessee have purchased the bottomland farm and paid for a house to be built on the land where Gracie and Alvin will start their married life.