Information about Pierre D’Assigny’s early life appears in William Prynne’s 1645 pamphlet ‘The Lyar Confounded’ wherein Pierre is called a “zealous popish monk” who left his orders “some say for incontinency”. But this reference was intended as defamation, and might not be trustworthy.
Another source, Jean Chevalier (who kept a diary in Jersey during the years 1643-1651 and is witness to much of Pierre's activity), called Pierre D’Assigny “an alien, who had been a monk, and changed sides, God knows why”.
A more romantic view comes from a letter written by Pierre’s son, Marius D’Assigny, in April 1709, stating that “my father…left his Contry and Relations for his Conscience, being descended from a Noble family of Britany.”
When Pierre D’Assigny was married on 20th November 1636, at the French Church, Threadneedle Street, London, to Elizabeth Marie, the marriage entry describes him as the son of Daniel D’assigny, deceased, and as being a native of Authon du Perche, France.
That's all I have found out about Pierre D'Assigny's pre-British life. His stated place of origin, Authon du Perche, is not in Britanny. The name D'Assigny is a prominent family in the Auxerre area of France, but I have not yet found any D'Assignys in Authon, and of the 16th/17th Century Breton D'Assignys that I have found, none are called Daniel or Pierre.
There were two members of the D'Assigny family who came to England from France in the time of Henry VIII and of Charles II. Interestingly the later one was the wife of a Pierre D'Assigny of the Auxerre branch, but any connection to the Pierre D'Assigny of Jersey is not known.
