Youthful locomotive engineer Johnnie Gray of the Watern and Atlantic Railroad has two loves in his life, his train engine, which he has named “The General,” and his girl friend Annabelle Lee. On a spring day in 1861 when Jonnie visits Annabelle in Marietta, Georgia, he learns that Confederate troops have fired upon Fort Sumter and joins the throng of Southerns attempting to enlist in the Confederate Army. When he is rejected because his skill as an engineer is deemed vital to the cause, Johnnie attempts to enlist under various disguises. The recruiting officer finally ejects him, causing Johnnie to exclaim, “If you lose this war don’t blame me.” When Johnnie is too upset to answer Annabelle’s father questions about enlisting, her father assumes Johnnie is shirking his patriotic duty. When Annabelle confronts Johnnie about enlisting, Johnnie tells her the truth, but Annabelle tells him not to speak to her until he is in uniform. A year later, in a Union encampment just north of Chattanooga, General Thatcher and his chief spy, Captain Anderson, make plans to sabotage the Confederate railroad: They will enter the South posing as civilians, steal a train then proceed North, burning every bridge along the way to cut off supplies to the southern troops. Union General Parker will advance to engage the Confederates in a surprise attack on day they steal the train. Meanwhile, in Marietta, Annabelle, who still shuns Johnnie, boards The General en route to visit her father, who has been wounded in the war. When all the passengers disembark at Big Shanty for dinner, except Annabelle, who is in the luggage car searching for her trunk, the disguised Union spies remove the pin to the passenger cars and steal the engine and luggage car. While Johnnie chases The General with a hand-operated car, the Union soldiers discover Annabelle and tie her up. Johnnie is than derailed and continues on a penny-farthing bike until he reaches the Confederate encampment in Kinston, where he convinces an officer to help him find the train. After Confederate troops are loaded into several railroad cars, Johnnie leaves the station piloting an engine called The Texas; however, he is so preoccupied with the chase that he fails to look behind him until miles down the track, where he realizes that the troop cars are not attached to the engine. Deciding to fight for The General alone, Johnny attaches a car with a canon he finds on the tracks. As he approaches The General, Johnnie attempts to load and fire the cannon, but he accidentally jostles it in the direction of his train. As Johnnie rushes to the front of the train to protect himself from the blast, the train rounds a bend causing the cannon to fire at the Union soldiers instead. The Union soldiers, now fearing for their lives, disconnect their last car in hopes of stopping The Texas. Johnnie spots the slowing car and tries to switch it onto another set of tracks; however, the Union soldiers then drop a log across the tracks,which derails the car. Johnnie, having just turned his head, is baffled when he finds the car has suddenly disappeared. As the Union soldiers throw more logs across the tracks, Johnnie runs to the cow-catcher at the front of the train and cleverly pushes the logs off the track. At a changing station, the Union soldiers switch tracks to divert Johnnie, but Johnnie connects back to the main rail. As the chase continues, Johnnie is so absorbed with cutting wood to feed his boiler that he does not notice the hundreds of Confederate soldiers fleeing south as General Parker’s victorious Union army advances. When he finally realizes he is crossing into enemy territory, Johnnie abandons his train and runs into the woods to hide. During a rainstorm that night, Johnnie sneaks into a home for shelter, but finds himself trapped under the dining room table when a group of Union officers seat themselves to discuss their battle plans. Johnnie learns that Union soldiers are planning a surprise attack for the following morning and that Annabelle is their prisoner. Later, as the others sleep, Johnnie manages to escape the dining room, change into a Union uniform and rescue Annabelle. They flee into forest, where lightening sends them running into each other’s arms. The next day, Johnnie decides they must warn the Confederates about the attack. After stuffing Annabelle into a sack, Johnnie loads her onto a freight car attached to The General and then takes off towards the South. As Union troops began a chase, Johnnie helps Annabelle into The General, then unpins the luggage car, thus hampering the Union car’s speed until they are able to remove the car. When Johnnie leaves the train to move a crosstie, Annabelle, unable to work the gears, runs the engine forward and backward, leaving Johnnie behind, until he finally catches the train. As they reach Rock River bridge, Johnnie sets the bridge on fire to hinder their pursuers. When Annabelle accidentally puts a burning log between Johnnie and the train, Johnnie tries to leap onto the train, but misses the track and falls straight in to the water below. Upon reaching southern territory, they rush to the Confederate headquarters, where Johnnie informs the commander of Union plans and Annabelle is reunited with her father. Soon after, the Confederate troops arrive at the bridge just as the Union soldiers attempt to drive the supply train over it. As a car plunges into the water, the Confederate Army fires at the approaching Union troops who are fording the river. Johnnie attempts to help by firing a cannon, but aims it in wrong direction. The blast breaks a dam upstream, flooding the river and washing out a whole line of approaching Union soldiers. Victorious, Johnnie returns to southern headquarters, where he is commissioned as a lieutenant and thus wins the love of Annabelle. When passing soldiers salute the new officer, Johnnie embraces Annabelle with his left hand, freeing his right hand to salute.