The Zong massacre was a mass killing of more than 130 enslaved African people by the crew of the British slave ship Zong over several days from 29 November 1781. The William Gregson slave-trading syndicate, based in Liverpool, owned the ship as part of the Atlantic slave trade. As was common business practice, they had taken out insurance on the lives of the enslaved Africans as cargo. According to the crew, when the ship ran low on drinking water after a series of navigational errors, the crew threw enslaved Africans overboard.