[1] He was taken prisoner at the Siege of Grand Pre during Father Le Loutre's War in Nova Scotia (1750).
[2] He was helped to gain his release by both his father Otho Hamilton and his father-in-law William Shirriff, both of whom were members of the Nova Scotia Council.
Jean-Louis Le Loutre had paid Mi'kmaq ransom for Hamilton's release.
Captain John Hamilton then married his third wife Ann Moore in Waterford, Ireland in 1777.
In 1754–55, Hamilton was supportive of Le Loutre and Chief Paul Laurent trying to negotiate a peace with the British.