Bernard-Anselme's brother was Joseph d'Abbadie de Saint-Castin, an Acadian military chief.
In 1704, Governor Brouillan asked Bernard-Anselme, then just 15 years old, to rally his tribe to help protect Acadia from British attacks.
In 1707, this request paid off and Bernard-Anselme fiercely help defend Port Royal against a siege by British colonial forces.
On October 31 that same year, Bernard-Anselme married Marie-Charlotte Damours de Chauffours in Port Royal.
He was ordered to keep the First Nations hostile to the British, and in immediately after the Battle of Bloody Creek in 1711 his Abenakis unsuccessfully attacked Annapolis Royal.