Which one among the following was the immediate cause of attack by Nawab Siraj-ud-daullah on Calcutta in 1756?

The immediate cause of Nawab Siraj-ud-daulah's attack on Calcutta in 1756 was the English East India Company's refusal to stop and demolish the unauthorized fortifications of Fort William. While the Nawab had several grievances, including the misuse of trade privileges (dastaks) and the granting of asylum to political fugitives like Krishna Das [3], the escalation to military action was triggered by the Company's defiance regarding military works. Siraj-ud-daulah ordered both the French and the English to cease fortifying their settlements in anticipation of the Seven Years' War; while the French complied, the English refused. This act of insubordination, coupled with the humiliation of the Nawab's envoys, led Siraj-ud-daulah to seize the Kasimbazar factory and subsequently capture Fort William on June 20, 1756 [1]. This sequence of events directly preceded the infamous 'Black Hole' incident [2].

Sources

1. [2] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 5: Expansion and Consolidation of British Power in India > Prelude to the Battle > p. 88
2. [3] History , class XI (Tamilnadu state board 2024 ed.) > Chapter 16: The Coming of the Europeans > Battle of Plassey (1757) > p. 258
3. [1] Modern India ,Bipin Chandra, History class XII (NCERT 1982 ed.)[Old NCERT] > Chapter 4: The British Conquest of India > British Occupation of Bengal > p. 66