A photograph of the site of the Black Hole of Calcutta. The Black Hole of Calcutta was a small dungeon in Fort William, India where troops of the Nawab of Bengal, Siraj ud-Daulah, held British prisoners of war after the capture of Fort William on June 20, 1756. It is alledged that 123 out of 146 prisoners held in impossibly cramped and horrendous conditions died, although there is some doubt as to the precise legitimacy of this account.