Explanation: The appointment of the East India Company (EEIC) as the Diwan of Bengal on 12th August 1765 was a pivotal moment in the history of British colonial rule in India. The Diwan was a position that held the authority to collect land revenue, which was a significant source of income and power in the region. The EEIC's acquisition of this position was a result of the Treaty of Allahabad, which was signed between the EEIC and the Mughal Emperor Shah Alam II.
To understand the context, it is essential to look at the events leading up to this appointment. The Battle of Plassey in 1757 marked the beginning of British dominance in Bengal. The EEIC, under the leadership of Robert Clive, defeated Siraj-ud-Daulah, the Nawab of Bengal, and installed Mir Jafar as the new Nawab. However, Mir Jafar's rule was unstable, and the EEIC continued to face challenges in consolidating its power.
In 1764, the EEIC defeated the combined forces of the Nawab of Awadh and the Mughal Emperor Shah Alam II in the Battle of Buxar. This victory gave the EEIC a strong position to negotiate with the Mughal Emperor. As a result, Shah Alam II signed the Treaty of Allahabad in 1765, which granted the EEIC the Diwani rights of Bengal, Bihar, and Orissa. This meant that the EEIC was now responsible for collecting land revenue in these regions, effectively giving them control over the economic resources of a large part of India.
The appointment of the EEIC as the Diwan of Bengal was a significant step in the process of British colonization. It allowed the EEIC to establish a stable revenue base and to exert greater control over the region. The Diwani rights were a crucial factor in the EEIC's ability to finance its military campaigns and to expand its influence across India.
It is important to note that the other options provided in the question are incorrect because they refer to regional rulers who did not have the authority to appoint the EEIC as the Diwan of Bengal. Mir Jafar and Siraj-ud-Daulah were Nawabs of Bengal, and Shuja-ud-Daulah was the Nawab of Awadh. None of these individuals had the power to grant Diwani rights, which was a prerogative of the Mughal Emperor.
In conclusion, the appointment of the EEIC as the Diwan of Bengal by Shah Alam II in 1765 was a critical event in the history of British colonialism in India. It marked the beginning of the EEIC's direct control over the economic resources of a significant part of the subcontinent, setting the stage for further expansion and consolidation of British power in India.