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.

Performing regimental duty in Canada, Germany, and Cyprus, de Chastelain subsequently attended the British Army staff college in Camberley in 1966 and was commanding officer of the Second Battalion PPCLI from 1970 to 1972.

As part of the Good Friday Agreement an independent neutral adjudicator was selected to look over the disarmament of Republican and Loyalist paramilitary weapons in Northern Ireland.