Which French fort at Crown Point was blown up by its garrison in 1759?

The French fort at Crown Point blown up by its garrison in 1759 was Fort Saint-Frédéric.

Built beginning in 1734 on Lake Champlain, Fort Saint-Frédéric guarded the northern approach to New France and helped the French control movement between the lake and the British colonies. Its position at Crown Point made it part of a defensive chain that also included Fort Carillon, later called Ticonderoga.

When General Jeffery Amherst’s large British army advanced in 1759, French forces abandoned Fort Carillon and withdrew northward. On July 31, Colonel François-Charles de Bourlamaque ordered Fort Saint-Frédéric destroyed before retreating toward Île-aux-Noix. The explosion damaged the fort and burned parts of it, but some masonry survived.

The British did not simply restore the old post. They began building the much larger Fort Crown Point beside the ruins in the autumn of 1759. This is the main source of confusion: Crown Point names both the geographic location and the later British fort, while Saint-Frédéric was the earlier French fort.