Siraj-ud-Daulah's nomination to the Nawab ship aroused the jealousy and enmity of his maternal aunt, Ghaseti Begum (Mehar-un-nisa Begum), Mir Jafar, Jagat Seth, Mehtab Chand and Shaukat Jung (Siraj's cousin). Ghaseti Begum possessed huge wealth, which was the source of her influence and strength. Apprehending serious opposition from her, Siraj ud-Daulah seized her wealth from Motijheel Palace and placed her under confinement. The Nawab also made changes in high government positions giving them his own favourites. Mir madan was appointed Bakshi (Paymaster of the army) in place of Mir Jafar. Mohanlal was elevated to the rank of peshkar of his Dewan Khana and he exercised great influence in the administration. Eventually, Siraj suppressed Shaukat Jang, governor of Purnia, who was killed in a clash.
Black Hole of Calcutta
Pindari's loyal to Siraj ud-Daulah carry out the Black Hole of Calcutta atrocity, 20 June 1756.
Siraj, as the direct political disciple of his grandfather, was aware of the global British interest in colonization, and hence resented the British politico-military presence in Bengal represented by the English East India Company. He was angered at the company's alleged involvement with and instigation of some members of his own court to a conspiracy to oust him. His charges against the company were broadly threefold. Firstly, that they strengthened the fortification around the Fort William without any intimation or approval; secondly, that they grossly abused trade privileges granted them by the Mughal rulers – which caused heavy loss of customs duties for the government; and thirdly, that they gave shelter to some of his officers, for example, Krishnadas, son of Rajballav, who fled Dhaka after misappropriating government funds. Hence, when the East India Company began further enhancement of military strength at Fort William in Calcutta, Siraj ud-Daulah ordered them to stop. The Company did not heed his directives; consequently, Siraj retaliated and captured Kolkata (for a short while renamed Alinagar) from the British in June 1756. The Nawab gathered his forces together and took Fort William. The captives were placed in the prison cell as a temporary holding by a local commander, but there was confusion in the Indian chain of command, and the captives were left there overnight, and many died. Contemporary British accounts of the ordeal run a considerable risk of embellishment. Actually the East India Company tried their best to propagate a false story of black hole killing among the people to raise them against Nawab Siraj ud-Daula.
Sir William Meredith, during the Parliamentary inquiry into Robert Clive's actions in India, vindicated Siraj ud-Daulah of any charge surrounding the Black Hole incident: "A peace was however agreed upon with Surajah Dowlah; and the persons who went as ambassadors to confirm that peace formed the conspiracy, by which he was deprived of his kingdom and his life."