John Bradstreet was born on December 21, 1714, at Annapolis Royal in Nova Scotia. He was the son of Lieutenant Edward Bradstreet, an officer in the British garrison, and Agathe de Saint-Étienne de La Tour, who descended from a prominent Acadian family. This mixed English and French colonial background gave him an unusual familiarity with the peoples, languages, and geography of northeastern North America. He grew up in a fortified settlement that had changed hands repeatedly between France and Britain and where military security, trade, and diplomacy were part of everyday life.

Bradstreet entered the British Army while young, probably benefiting from his father’s connections within the garrison. He served as an ensign in the 40th Regiment of Foot, one of the principal units stationed in Nova Scotia. His early duties included garrison administration, communication with neighboring communities, and the movement of supplies through a region where roads were scarce and waterways provided the most practical routes. He became particularly knowledgeable about boats and military transportation.

During King George’s War, Bradstreet participated in the 1745 New England expedition that captured the French fortress of Louisbourg. He helped organize transport and supply, gaining recognition for practical energy rather than social rank. After Louisbourg was returned to France, he continued serving in British North America and developed ties with colonial officials and merchants. He also married Mary Aldridge, connecting himself with a family prominent in Nova Scotian administration.

By the early 1750s Bradstreet had become an experienced colonial officer and logistician. He understood that armies operating between the Hudson River, Lake George, and Lake Ontario depended on bateaux, fortified depots, and reliable crews. His ability to move men and provisions across inland waters would make him indispensable when renewed imperial rivalry turned the northern frontier into a major theater of war.