Guillaume Longpré was taken prison in the attack on Deerfield on 22 August 1703. Taken capture by the Abenaki Indians. While living with the Abenakis, he participated in fur trade journeys for many years until he was an adolescent, before he established himself in Montreal.

On 15 January 1720, Guillaume II, married Catherine BLEAU who was born in 1699, the daughter of François BLEAU & Catherine CAMPEAU (per notary contract with LEPAILLEUR 1720/01/14). Following their marriage, the LONGPRE couple settled in Montreal, then Pointe-aux-Trembles where their 10 children were born between 1720 & 1738.