The father of Siraj was Zain Ud Din, who was the ruler of Bihar and his mother Amina Begum Nawab Alivardin's youngest daughter. Since Nawab had no son, Siraj Ud Daullah, as the Nawab's grandson, got very close to him and therefore his childhood was regarded by most people as successor to Mutshidabad's throne. He was raised accordingly at the palace of the Nawab with all required training and education necessary for a future Nawab. Young Siraj accompanied Alivardi in the year 1746, in his military endeavour against the Marathas. In the year 1752, Alivardi Khan officially announced his grandson Siraj-Ud-Daullah as the successor and Crown Prince to the throne, making not a single division in the royal court and the family.
Mirza Muhammad Siraj succeeded Alivardi Khan as the new Nawab of Bengal in the month of April 1756 and he took the name of Siraj-Ud-Daullah. His nomination to the Nawabship triggered the enmity and jealousy of Ghaseti Begum, the eldest daughter of Alivardi, Mirjafar Ali Khan, Raja Rajballav, and Shawkat Jung (the cousin of Siraj). Ghaseti Begum had huge wealth, and that was the source of her strength and influence.Siraj seized her wealth and kept her in confinement. He offered top post to his favourites , Mir Madan who became the Bakshi(the paymaster of the arrmy) replacing Mir Jafar. Mohanlal was promoted to the rank of peshkar of his Dewan Khana and he had a vital influence in the administration. Lastly, Siraj suppressed Shaukat Jung , who was the governor of Purnea and was also killed in a clash.
