(i) In 1760 the British deposed Mir Jafar from the nawabship of Bengal and placed Mir Qasim as the new Nawab of Bengal. The British made him nawab in the hope that he would be able to meet their financial demands.

(ii) The new Nawab assigned to them the district of Burdwan, Midnapore and Chittagong for the expenses of the British army which was to help him.

(iii) This alliance was of great help to the British in their campaign against the French in 1760-1761; the money paid by Mir Qasim helped the Calcutta Council to finance their war in the south.

(iv) The Nawab succeeded in establishing a better system of administration. But he came into conflict with the British in Bengal on the question of a privilege i.e. duty free private trade of the Company.

(v) Mir Qasim's proposed plan about equal duties for British and Indian traders was turned down by the British Council at Calcutta. Mir Qasim, in the circumstances, remitted all duties on Indians and the British alike for two years. This measure deprived the British private traders of the privileged position they had created for themselves, they could not compete with Indian traders on equal terms. 

(vi) The Nawab's attempts to reorganise the army and shifting of capital from Murshidabad to Monghyr were also taken as unforgivable offences by the Company.

(vii) In June 1763 under Major Adams British army defeated Mir Qasim the Nawab of Bengal. Mir Qasim fled to Patna and took help from Emperor Shah Alam II and Shuja-ud-Daula (Who was Nawab of Awadh and also the Wazir of the Mughal empire).