In 1765 after the victory in the Battle of Buxar the British had formally gained Dewani of Bengal and Bihar from Shah Alam II.

Najmuddin died soon afterwards, on 8 May 1766, apparently from a fever caught at a formal party given at Murshidabad fort in honour of Robert Clive.

[citation needed] After the death of Mir Jafar Nawab Nazim Najm-ud-din Ali Khan succeeded him to the Nawab's throne under the titles of Shuja-ul-Mulk (Hero of the Country), Nazam-ud-Daulah (Star of the State) and Mahabat Jang (Horror in War) at the age of 15 on 5 February 1765; it was confirmed by the East India Company on 23 February 1765.

[citation needed] Nawab Nazim Najm-ud-din Ali Khan died on 8 May 1766, of fever he caught at a party, which was given in honour of Robert Clive.

Najabat Ali Khan, Nazim-ud-din's brother, according to Mohammedan law was the right successor of the late Nawab, on the throne.