British prisoners of war were imprisoned in the ‘Black Hole of Calcutta’ after the Bengali army captured Fort William from the East India Company.
The East India Company had built Fort William to guard their trading base at Calcutta at a time when the provincial governors of the Mogul empire, known as nawabs, wielded significant power. The Nawab of Bengal, Siraj-ud-daula, was concerned that the Company had begun to strengthen the fort in response to French interests in the area. Fearing that a stronger fortress would undermine his own political power in the province, he ordered the work to stop. When the British refused to comply he sent an army of a reported 50,000 soldiers, 500 elephants and 50 cannon to lay siege to the fortress.
The nawab’s army met very little resistance as it advanced through Calcutta towards the fort, so the majority of British residents fled to the ships in the harbour. A small garrison remained in the fort under the command of John Zephaniah Holwell, an inexperienced military commander whose primary role was as a tax collector.
Unable to defend the fortress, Holwell was forced to surrender on the afternoon of 20 June. He later reported that at 8pm 146 people were imprisoned in the fort’s tiny 4.30m. × 5.50m lock-up, of whom only 23 survived the night due to heat exhaustion and suffocation. Reports of the incident prompted a mixture of British anger and patriotism, and led to a violent retaliation by Robert Clive the following year.
It is now known that Holwell’s figures were exaggerated, but a comprehensive study of the incident undertaken by Professor Brijen Gupta in the late 1950s concluded that of the lower number of around 64 prisoners, only 21 came out alive the next morning.