NCTB

60 Religious Books, The Ramayana, And The Mahabharata

They advised Ravana to give back Sita without any war. Ravana
decided not to give back Sita. He scolded Vibishana. Vibishana
deserted Ravana and joined hands with Rama.

War between Rama and Ravana

Fierce fighting started between the two armies. The war had been
fought for some time. A great number of troops on both sides were
killed. Many were wounded. Ravana's all sons were killed. One of
his sons was Indrajit. Ravana's brother Kumbhakarna also died. At
last Ravana came to the battle field. Rama killed Ravana with the
weapon named Brahmaastra.

After Ravana's death Vibishana became the king of Lanka. Rama,
Sita and Lakshmana went back to Ayodhya.