The Black Hole of Calcutta incident refers to forty three British soldiers and their Indian comrades in arms who perished in the Fort William brig, June 20, 1756. The events leading up to the Black Hole of Calcutta involved a campaign by the Nawab of Bengal, Siraj ud-Daulah against the British East India Company security forces in Calcutta. In June 1756, he marched on the Company's settlement with a sizable force of 30,000 foot soldiers, 20,000 horsemen, 400 trained elephants and eighty pieces of cannon. Faced with overwhelming superiority, most of the British soldiers fled along with their Indian troops. Siraj-ud-Daula took captive the few who remained, putting them into the brig at Fort William for the night.
The brig had been called the Black Hole by the British, and the name stuck after the events of the night had passed. June 20, 1756, proved a sweltering night, forty three of the sixty four prisoners perishing from heat exhaustion and suffocation. Robert Clive, the man who proved most important in establishing of the British East India Company as a colonial power in India, led a putative expedition, defeating Siraj-ud-Daula and the Marathas. Clive continued over the next eleven years, until 1766, when he left India, to set up the British East India company in firm control of much of India. The Black Hole of Calcutta had given him the entrée to set Great Britain on the path to ruling India until 1947.