The two battles fought for the control over Bengal between the Nawabs and British were the Battle of Plassey and the Battle of Buxar.

1. Battle of Plassey:
- The Battle of Plassey took place on June 23, 1757, between the forces of the Nawab of Bengal, Siraj-ud-Daulah, and the British East India Company.
- The British East India Company, under the leadership of Robert Clive, had established a strong presence in Bengal and wanted to expand their control over the region.
- Siraj-ud-Daulah, the Nawab of Bengal, was opposed to the growing influence of the British and wanted to assert his authority.
- The battle was fought near the village of Plassey (now in West Bengal) and resulted in a decisive victory for the British.
- The British forces, with the help of Mir Jafar, a disloyal general in Siraj-ud-Daulah's army, managed to defeat the Nawab's forces.
- The main reason for the British victory was the betrayal of Mir Jafar, who switched sides during the battle.
- The Battle of Plassey marked a turning point in Indian history as it established British control over Bengal and laid the foundation for their subsequent conquest of India.

2. Battle of Buxar:
- The Battle of Buxar was fought on October 22, 1764, between the forces of the British East India Company and a coalition of Indian rulers, including the Nawab of Bengal, the Nawab of Awadh, and the Mughal Emperor Shah Alam II.
- The Indian rulers formed an alliance to resist British expansion in the region and to regain control over Bengal.
- The British East India Company, under the leadership of Hector Munro, defeated the coalition forces in a decisive battle near the town of Buxar (now in Bihar).
- The defeat of the Indian coalition was mainly due to the superior military tactics and firepower of the British forces.
- The Battle of Buxar resulted in the Treaty of Allahabad, signed in 1765, which further consolidated British control over Bengal.
- According to the treaty, the Mughal Emperor Shah Alam II granted the Diwani rights (rights to collect revenue) of Bengal, Bihar, and Orissa to the British East India Company.
- The Battle of Buxar marked another significant step in the British conquest of India and paved the way for their subsequent control over large parts of the country.

Overall, the battles of Plassey and Buxar played a crucial role in establishing British dominance over Bengal and laid the foundation for their subsequent colonization of India. These battles marked a turning point in Indian history and had far-reaching consequences for the future of the country.