Behind the smokehouse on the Sartoris plantation, Bayard and Ringo drawi a map of the battle of Vicksburg in the dirt with wood chips and a hoe. They look up to see Loosh, a slave, standing over them, red-eyed and frightening. Loosh's wife Philadelphy tells him to leave the boys alone, but instead he knocks their map flat with his hand, a triumphant expression on his face. He smugly hints something about Corinth, Mississippi that the boys do not understand. Loosh implies that Bayard's father, Colonel John Sartoris, is in Corinth rather than in Tennessee, where Bayard still believes the front lines are. When Loosh and Philadelphy leave, Bayard and Ringo speculate about whether the armies are really at Corinth. Instead of finishing their map, they decide to play at being soldiers, but Ringo insists on playing Confederate General Pemberton rather than Union General Grant. As the boys horse around, Louvinia shouts at them to look up the road, where they see Colonel Sartoris riding toward them. Awestruck, Bayard stares at his father as he greets the family and orders his horse stabled, admiring the "smell of glory" in his father's clothes. Granny Millard greets the colonel stoically and unemotionally.
That afternoon, Bayard, his father, and several slaves build a livestock pen in the creek bottom. Colonel Sartoris works "faster and harder than anyone else." Bayard is thrilled to be taking orders from the father he adores, imagining himself as one of the colonel's soldiers. As the sun sets, they finish the fence and drive the livestock into the pen. Before dinner, Bayard notices that the family's silver has been packed away in the attic. Bayard hopes his father will tell stories about the war, but after supper he sends the boys to bed instead. Eavesdropping upstairs, Bayard hears the adults planning to bury the silver now that Vicksburg has fallen. The next morning, Colonel Sartoris is gone.
To entertain the boys as it rains, Granny Millard reads cake recipes aloud from the cookbook while Ringo tries to decide whether or not he has ever tasted coconut cake. When the sky clears up, Ringo and Bayard sneak outside to keep an eye on Loosh, because Bayard has overheard his father saying Loosh knows about the Confederate defeat. They watch him for several days. One night, they see him riding off down the road toward Corinth; when he returns a day later, his clothes are torn and muddy. He tells the other slaves that the Yankees plan to free them, but they angrily tell him to be quiet. Bayard and Ringo, who know something is about to happen, hide in a cedar grove and watch the road for two days.
One afternoon, Ringo awakens Bayard from a nap and points to a Yankee soldier on horseback who is staring at the house. The boys sneak out of the grove, run to the house and drag a musket off the wall. They carry it to a hedge by the road and, as Bayard balances the gun on Ringo's back, he fires at the soldier. A moment later, Ringo screams that "the whole army" has arrived. The boys run yelling into the house and tell Granny they've killed a Union soldier; at the same moment, they hear soldiers' boots on the porch. Granny, terrified but quick-witted, hides the boys under her rocking chair and drapes her skirts over them. A Yankee sergeant barges into the house and demands at gunpoint that Granny turn over the boys. She insists, poker-faced, that there are no children in the house and invites them to search. When the sergeant says he is angry because the boys have killed a horse that the regiment planned to bet on, Granny is visibly relieved to learn that no soldiers are dead. The sergeant is oblivious, but a Yankee colonel who enters the house immediately understands the game Granny is playing, teasingly telling her what a shame it is she has no grandchildren, especially not a grandson and a slave playfellow. He adds that he hopes she will have nothing worse with which to remember the Union army, and leaves. As soon as they are alone, Granny ignores the incident but washes out the boys' mouths for swearing. Kneeling, she asks God to forgive her for lying to the officers.
The Unvanquished is a bildungsroman—a novel in which a protagonist develops and matures to adulthood. Such novels often begin with a depiction of pure childhood, a time before crises and life lessons begin to shape the character, when innocence is still intact. "Ambuscade" depicts Bayard in a state of perfect naïvetè: the Civil War may be raging around his family, yet to him it is nothing more than a glorious game. The boys' game of soldiers is a literal illustration of this innocence. Bayard wants to play General Pemberton, the Confederate commander of the stronghold at Vicksburg, even after Loosh has implied to him that Vicksburg has fallen and Pemberton has surrendered. As a boy, Bayard loves nothing more than exciting war stories, but the awful reality of the fighting is inaccessible to him. Even his first sighting of Union troops results in nothing more than a brilliant adventure and a heart-stopping story—adults like Granny and Colonel Dick are still conspiring to protect him. When Granny washes the boys' mouths for cursing, she restores the security of everyday routine and implies that cursing is the worst thing a person can do. This mundane punishment, contrasted with the very real danger of war, shows the contrast between child and adult worlds.
Bayard is also ignorant of the politics that motivate the fighting, especially regarding race. At one striking moment, he excitedly tells Granny that the Yankees are coming to set them all free—he is simply echoing one of Loosh's comments, and is unaware of the difference in status between himself and Loosh. The realities of race are all around him, but he cannot see them—cannot understand why it is unfair that Ringo should only be allowed to play the coveted Confederate general one out of every three games. Bayard speculates that owing to their intimacy, "maybe he wasn't a nigger anymore or maybe I wasn't a white boy anymore " We might imagine the whippings, the hard labor and unending humiliation of slave life would have taught Bayard about the real difference between white and black, but those hardships are absent from "Ambuscade"—in fact, largely absent from the novel altogether.