On June 16, 1756, Nawab of Bengal Siraj-ud-Daulah, outraged by the British East India Company’s refusal to stop fortifying Kolkata in anticipation of the Seven Years’ War, began his attempt to capture Kolkata and took up position behind the Maratha ditch.
The British were unprepared and Siraj would capture Kolkata. On June 20, this would lead to the Black Hole episode, when a number of captive Europeans would be killed.