There's some foreshadowing of the fact that Atlanta is going to come under siege.
Aunt Pittypat has a little party to entertain people and distract them from the war, and Rhett shows up, bringing his scandalous realism about the war with him.
More about the war: Confederates are holding, but it's only a matter of time.
Scarlett is doing a lot of nursing, which is really unpleasant.
She escapes from the hospital, finds Rhett, and he takes her riding in his carriage.
They run into Big Sam, who'd been a foreman on Scarlett's plantation.
He's singing "Go Down, Moses" as they head out to work on the fortifications around town.
This is especially ironic since "Go Down, Moses" is a song about freeing the Jews from enslavement in Egypt, but Mitchell has her slaves just cheerful and happy to be enslaved.
Scarlett realizes there's going to be a siege of Atlanta, and is justly freaked out.
Rhett says he's going to stay to see how things go, but he's probably lying—he's totally staying because he's sweet on Scarlett.
He teases her about Ashley Wilkes and figures out he kissed her and she is waiting for him helplessly.