Ravana sends skilled soldiers and family members to try to protect Lanka, but nobody returns. He tries to infiltrate Rama's ranks with spies, but this proves ineffective. Finally, he tries to convince Sita that Rama is dead by showing her a decapitated head that looks like Rama's, but Sita refuses to believe the head actually belonged to her husband.
Notice that two of Ravana's three tactics utilize manipulation or deceit. This continues to paint Ravana as a deceitful and evil character, while suggesting that honesty and loyalty (as Sita demonstrates here) are more powerful than manipulation.
Rama sends Angada as a messenger to Ravana to ask him to concede, and share that Rama supports Vibishana's claim as king of Lanka. Ravana orders his rakshasas to kill Angada, but Angada picks up two of them, rises into the sky, and throws them down. On his way out of the city, Angada also breaks off the tower of Ravana's palace. When Angada returns to Rama with an account of what happened, Rama orders his armies to attack Lanka.
Like Hanuman did during the first infiltration of Lanka, Angada attacks Ravana's love of demonstrating his power through material goods. Angada sends a clear message to Ravana that his unlawful actions have consequences, and notably, he and Rama give Ravana the chance to decide to concede this fight.
The battle rages for days. Indrajit at one point attacks Rama and Lakshmana with arrows that make them faint. This pleases Ravana, as he thinks they're dead. He sends Sita into the sky in a chariot to observe her "dead" husband, and Sita cries and wants to die. One of Ravana's women, however, whispers in Sita's ear that Rama and Lakshmana aren't actually dead. Soon, an eagle appears to neutralize Indrajit's arrows and Rama and Lakshmana rise to rejoin the fight.
This intelligence from Ravana's woman shows that his subjects might not be as loyal as Ravana thought they were. This creates the sense that Ravana is unable to cultivate a loyal following like Rama has been able to, which works to elevate Rama as the ideal hero and show that Ravana's evil has more negative consequences.
Ravana sends his commander-in-chief onto the battlefield, but the commander doesn't return. Ravana then decides to join the battle himself. Lakshmana faints at the sight of Ravana, but Hanuman lifts Rama onto his shoulders and they attack Ravana. Rama severely wounds Ravana and breaks his crown. Rama then sends Ravana back to his palace to recoup and fight again the next day, and Ravana agrees, humiliated.
Breaking Ravana's crown is another symbolic attack of Ravana's overt displays of power. Rama shows that he's honorable and kind by allowing Ravana the time to recoup. Though it'd be faster to kill Ravana at this point, Rama places too much importance on insuring that this fight proceeds honorably.
Ravana orders a small army to wake Kumbakarna, who is famous for his deep sleep. They offer him food and water when he finally wakes up, and then Ravana's minister gives him an account of the battle raging outside. Kumbakarna is angry that he wasn't told of the battle earlier, and he rushes to Ravana to assure him that he'll take care of Rama. Kumbakarna is surprised to see Ravana look so anxious. Kumbakarna says that Ravana should've never gone about stealing Sita in this way, driven by lust. He promises to bring Rama's head on a platter.
Kumbakarna doesn't present himself as a wholly evil character; he's fully able to admit that Ravana isn't a beacon of heroism like Rama is. Kumbakarna is, however, bound by loyalty to his brother. Even if he thinks that Ravana is in the wrong, he must serve him until he can serve him no longer. Ravana does seem to be cracking under the pressure of this battle.
Though Kumbakarna's presence on the battlefield causes mayhem, Rama manages to use his bow and kill him. When Ravana hears of this development, he cries that his "right hand is cut off." Indrajit, meanwhile, creates a fake figure of Sita, carries the figure onto the battlefield, and kills her in front of Rama's army. The monkeys grieve until Vibishana tells them it's a hoax.
Rama's bow is powerful enough to kill even the massive and dangerous Kumbakarna, which is indicative again of Rama's power and predestined heroism. Vibishana continues to show Rama that he's loyal to Rama's cause by shattering the illusions created by Ravana's brothers.
Later, Lakshmana kills Indrajit. Ravana cries and decides to kill Sita. Some of Ravana's advisors think this is a good idea, but others instruct Ravana to use his anger to kill Rama, which will then give him the right to take Sita as his own.
Some of Ravana's advisors appear to believe that he can still win Sita honorably and encourage him to take that path. Again, this suggests that not all who serve Ravana are evil.