Clive decided to overthrow Siraj-ud-daulah when Siraj began to favour the French. Clive won over some of the members of Siraj’s court, including the commander-in-chief Mir Jafar.
Intrigues followed, leading to the Battle of Plassey in 1757between Siraj and the English East India Company. Siraj was defeated and killed. Mir Jafar, who became the new ruler of Bengal, rewarded the East India Company with a large sum of money, the zamindari (right to collect revenue) of Twenty-four Parganas, and free trade. The victory at Plassey thus transformed the Company from a mere trading institution to a political force in Bengal. It also exposed the weakness of the Indian political system. Mir Jafar failed to meet the Company’s heavy monetary demands. So, in 1760, the Company deposed Mir Jafar and made his son-in-law Mir Qasim the Nawab of Bengal. In return, Mir Qasim gave to the Company the zamindari of Burdwan (Barddhaman), Midnapore (Medinipur) and Chittagong.