LitCharts assigns a color and icon to each theme in Coriolanus, which you can use to track the themes throughout the work.
Politics, Class, and Rome
Language and Names
War, Violence, and Masculinity
Family and Femininity
Heroism vs. Humanity
Summary
Analysis
Before the gates of Corioles, Lartius orders Roman soldiers to take up guard posts. If needed, these soldiers should come to aid the rest of the army, since a loss in the battle field will mean the loss of the city. A lieutenant agrees to obey the orders, and Lartius orders the new guards to shut the gate, and then he heads to the Roman camp.
This quick scene is simple military explanation, showing that (thanks to Caius Martius) Rome is now in control of the city of Corioles.