Nana Sahib was the successor to Peshwa Baji Rao II.

Nana Sahib, whose original name was Dhondu Pant, was born in 1824 in the Bithoor district of present-day Uttar Pradesh, India. He was the adopted son of Peshwa Baji Rao II, who was the last ruler of the Maratha Empire.

Nana Sahib's Rise to Power:
1. Adoption by Peshwa Baji Rao II: Nana Sahib was adopted by Baji Rao II, as the Peshwa had no legitimate heir. This adoption was done to ensure the continuity of the Peshwa dynasty and the Maratha Empire.
2. Training and Education: Nana Sahib received a good education and military training under the guidance of his adoptive father. He learned about administration, warfare, and the functioning of the Maratha Empire.
3. Growing Influence: Nana Sahib gained popularity among the Maratha nobles and the local population due to his intelligence, charisma, and leadership skills. He became a prominent figure in the Maratha court and was considered as a potential successor to the Peshwa throne.

The Rebellion of 1857:
1. Annexation of Oudh: In 1856, the British East India Company annexed the kingdom of Oudh, which was ruled by Wajid Ali Shah. This event led to widespread discontent among the Indian soldiers and nobles, including Nana Sahib.
2. Revolt in Kanpur: When the Indian Rebellion of 1857 broke out, Nana Sahib played a significant role in organizing the rebellion in Kanpur. He led the uprising against the British and managed to capture the British garrison in Kanpur.
3. Siege of Cawnpore: Nana Sahib's most infamous action during the rebellion was the Siege of Cawnpore. He lured a large number of British men, women, and children into surrendering under the promise of safe passage. However, he later ordered their massacre, which shocked the British and led to a brutal retaliation.
4. Legacy and Disappearance: After the British regained control of Kanpur, Nana Sahib fled and his whereabouts remained unknown. There are various theories about his fate, including the possibility of his death in exile or escape to Nepal.

In conclusion, Nana Sahib was the successor to Peshwa Baji Rao II and played a significant role in the Indian Rebellion of 1857. However, his actions during the rebellion, particularly the Siege of Cawnpore, have left a controversial legacy.