John de Chastelain

Alfred John Gardyne Drummond de Chastelain CC CMM CH CD (born 30 July 1937) is a Canadian retired army officer and diplomat.

De Chastelain was born in Romania to Scottish and American parents and was educated in England and Scotland before his family emigrated to Canada in 1954. There, de Chastelain became a Militia private and enrolled in the Royal Military College of Canada, going on to pursue a career in the Canadian Army. He was commissioned into Princess Patricia's Canadian Light Infantry and rose eventually to be twice Chief of the Defence Staff, with a break of a year during which he served as Canada's ambassador to the United States. In 1995, de Chastelain became active in the Northern Ireland peace process and eventually focused on the disarmament of paramilitary groups in Northern Ireland.