Siraj ud-Daulah, the last independent Nawab of Bengal resented the military presence of the British in Bengal, represented by the British East India Company. He found it objectionable, as the company had already strengthened the fortification around the Fort William without any prior intimation and approval. They also grossly abused the trade privileges granted to them by the Mughal rulers, which caused heavy loss of customs duties for the local government. Apart from that, the company gave shelter to some of his offending officers, who fled Dhaka after misappropriating government funds. Even after that, when the East India Company started to further enhance their military preparedness at Fort William in Calcutta, Siraj could not tolerate it anymore and asked them to stop the procedure immediately. However, the British East India Company did not pay any heed to it.
As a result of the British indifference to his authority, the infuriated Nawab organized his army and marched towards Calcutta with 50,000 soldiers, 500 elephants and fifty cannons. The army arrived on June 16th, and began to move slowly through the outskirts of Calcutta, overwhelming all the resistances. He captured Calcutta from the British Company in June 1756, and sieged their strong hold, the Fort William. After two days of continuous fighting, Roger Drake, the administrator, found it impossible to defend anymore and somehow escaped to Phalta on 19 June, along with some of the surviving soldiers. At the same time, to provide sufficient cover for his escape and to put up a show of dedicated fight, Drake left behind a number of Anglo-Indian soldiers and civilians, under the command of one John Zephaniah Holwell, who was not at all a military person, an ordinary civilian, a senior bureaucrat of the East India Company. Nevertheless, the fighting ceased, as Holwell surrendered in the evening of 20 June and the prisoners were crammed into a rather small cell measuring 14 feet by 8 feet and served by only two small windows, as a temporary custody by a local commander.
It seems that, there was some ambiguity or misunderstanding somewhere in the chain of command of the Nawab’s army, due to which all those captives were unintentionally left in that overcrowded stuffy prison to suffer all through the night. It ended in an infamous tragedy, with the unfortunate death of 123 persons, out of 146, who lost their lives due to suffocation and heat.
The relative cell, as described above, was known as ‘Black Hole’, even before the infamous incident of 1756 and the incident was later vividly described by the said John Zephaniah Holwell in his account. Apart from that, he also took the initiative to erect a tablet on the site of the cell and named it the 'Black Hole Tragedy’ to commemorate the victims. Strangely, the plaque somehow disappeared from the site before 1822.
However, many historians have strongly criticized Holwell’s account, claiming it to be extremely exaggerated and that Holwell was actually encouraged to do so, by the British government as they were just looking for a reasonable excuse to declare war against the Nawab. According to them, it is simply impossible to confine nearly 150 persons in a room of that size. Stanley Wolpert, a reputed historian remarked that, Siraj ud-Daulah can never be blamed for the fatal incident, he did not order the imprisonment and was not at all informed of it. According to Ramesh Chandra Mazumder, Holwell’s account is only a baseless story and cannot be considered as a reliable historical document. In a comparatively new study in 1959, Professor Brijen Gupta opined that the unfortunate incident did occur and out of 64, number of survivors was 21.
After more than a century of the incident, when Lord Curzon came to Calcutta as the Viceroy in 1899, he was surprised to notice that there was nothing to mark the spot of the Black Hole. He took the initiative and at his instance an unimpressive obelisk was installed between the General Post Office and the Writer’s Building. But, during the exciting days of the Indian National Movement for independence in 1940, the British had to remove the so called Holwell monument from the southwest corner of the Writer’s Building in July 1940 and rehabilitated it at the spacious compound of St. John’s Church.
It is needed to be mentioned here that, the narrow passageway by the northern side of the present building of the General Post Office was the site of the guardroom of the old Fort William, which was used as the infamous 1756 Black Hole of Calcutta. The said guardroom disappeared shortly after the incident when the fort itself was taken down to be replaced by the new Fort William. The memorial plaque can now be found in the nearby postal museum.