April 28, 1818: The Rush-Bagot Treaty
On April 28, 1817, Acting United States Secretary of State Richard Rush and the British Minister to Washington Sir Charles Bagot signed and exchanged letters that became the Rush-Bagot Agreement or Treaty, which demilitarized Lake Champlain and the Great Lakes.
The agreement provided for demilitarization of the lakes along the international boundary, where many British naval arrangements and forts remained. The treaty stipulated that the United States and British North America could each keep one military vessel (of no more than 100 tons) as well as one cannon (no more than eighteen pounds) on Lake Ontario and Lake Champlain. It later extended this to the other Great Lakes and to the entire Canadian border.
The USA and Canada have worked well together at cleaning up the lakes and keeping them demilitarized. The US Coast Guard now has bigger guns, but Canada looks the other way. According to Wikipedia, “The Canadian government decided that the armament did not violate the treaty, as the guns were to be used for law enforcement rather than military activities. Canada reserved the right to arm its law enforcement vessels with similar weapons.”
More About Lake Champlain History: