Diwan Mohanlal was a Diwan of Siraj Ud Daulah, the Nawab of Bengal

Nawab of Bengal

The Nawabs of Bengal were the hereditary nazims or subadars of the subah of Bengal during the Mughal rule and the de-facto rulers of the province.-History:...

 at Murshidabad

Murshidabad

Murshidabad is a city in Murshidabad district of West Bengal state in India. The city of Murshidabad is located on the southern bank of the Bhagirathi, a distributary of the Ganges River. It was the capital of undivided Bengal during the Mughal rule. Nawabs of Bengal used to rule Bengal from this...

, (r. 1756 - 1757). The Nawab made the decision of elevating a Hindu

Hindu

Hindu refers to an identity associated with the philosophical, religious and cultural systems that are indigenous to the Indian subcontinent. As used in the Constitution of India, the word "Hindu" is also attributed to all persons professing any Indian religion...

 kayastha

Kayastha

Kayastha or Kayasth or Kayeth is a caste or community of Hindus originating in India. Kayastha means "scribe" in Sanskrit, and has traditionally denoted members of the writer caste....

 bureaucrat named Mohanlal as his supreme Diwan. The elevation of a Hindu to such a prominent position caused the Muslim

Muslim

A Muslim, also spelled Moslem, is an adherent of Islam, a monotheistic, Abrahamic religion based on the Quran, which Muslims consider the verbatim word of God as revealed to prophet Muhammad. "Muslim" is the Arabic term for "submitter" .Muslims believe that God is one and incomparable...

 nobility, and in particular Mir Jafar

Mir Jafar

-Notes:# "Riyazu-s-salatin", Ghulam Husain Salim - a reference to the appointment of Mohanlal can be found # "Seir Muaqherin", Ghulam Husain Tabatabai - a reference to the conspiracy can be found...

, great offence. Mir Jafar was then the head of the armed forces, second only to the Nawab, and the elevation of a Hindu to a post above him was taken almost as a personal insult.

On the day of the Battle of Plassey

Battle of Plassey

The Battle of Plassey , 23 June 1757, was a decisive British East India Company victory over the Nawab of Bengal and his French allies, establishing Company rule in South Asia which expanded over much of the Indies for the next hundred years...

, Siraj-Ud-Daulah faced off against the British, apparently with overwhelming force, but at the critical time Mir Jafar's men stood watching passively while the soldiers of Siraj-Ud-Daula were decimated by the smaller but much better armed British forces.

Mohanlal has been portrayed as a great patriot and the most trusted lieutenant of the nawab in the famous Bangladeshi movie Sirajud Daulah