The fortification of Calcutta by the British in 1756 was regarded by the Nawab of Bengal, Siraj- ud- da ul ah, as—

In 1756, the British East India Company began strengthening the defenses of Fort William in Calcutta, citing potential hostilities with the French [2]. However, the new Nawab of Bengal, Siraj-ud-Daulah, viewed these unauthorized fortifications as a direct challenge to his authority and an attack upon his sovereignty. He perceived the British actions—which included interfering in local politics and protecting his political rivals—as a sign of their growing territorial ambitions beyond mere commerce. Siraj-ud-Daulah issued orders for the British to cease their fortification work immediately. When the British Governor ignored these commands, the Nawab regarded it as an act of defiance against his rule, leading him to march on Calcutta and seize Fort William in June 1756 to assert his sovereign control over the region [2].

Sources

1. [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