The Waterways Disputes
A significant portion of the border between the United States and Canada is water, and the ports of the Great Lakes are connected to the sea via canals and the St. Lawrence Seaway. During the War of 1812 the Great Lakes and other waterways were the scenes of significant fighting between the British and the Americans, and their strategic importance became obvious. As America grew to the west following the war, several treaties were negotiated and ratified between the British and Americans pertaining to armed vessels on the Great Lakes and other waterways.
Essentially the American and British governments agreed to the demilitarization of the border between the United States and Canada, beginning with the Rush-Bagot Treaty in 1818 (which also agreed to joint occupation of the Oregon Territory). The treaty created the longest demilitarized border in the world. The remains of the British fleet on the Great Lakes were dismantled. The American fleet was withdrawn. Nonetheless both the United States and Canada retained military facilities on the lakes and at other locations, including along the Niagara River. Defense posts just inland remained as well, some still today.
During the First World War the treaty remained in effect. During the Second World War both Canada and the United States worked together to violate its language. It was agreed that warships built along the Great Lakes could be armed, as long as the arms were not ready for use until the ships on which they were installed were no longer on the waters involved. The Americans and Canadians later decided that the treaty did not restrict the presence of armed vessels which were operating in a training capacity. The same philosophy was applied to the presence of shore based guns along the lakes since training was not a hostile violation of the treaty.
This agreement between Canadian and American authorities allowed the historically important treaty to remain in effect, though the activities along the lakes were in violation of its terms. Critically important training at the Great Lakes Naval Station on Lake Michigan would not have been legal under the terms of the treaty had not both sides agreed to essentially look the other way. Fully armed combat ready vessels were allowed on the waterways as long as both sides were fully informed in advance. This was critical for allowing combat vessels requiring refits or repairs to have access to the shipyards on the Great Lakes.
Post World War II Canada and the United States agreed to allow warships to be stationed on the Great Lakes for training purposes, which remains in effect in the twenty-first century. Additional co-operation between the two countries is evident in the United States’ decision to arm Coast Guard cutters and patrol boats in 2004, in response to an increase in smuggling and as part of the security requirements of the global war on terror. The Canadian government agreed that the vessels are not military vessels, but are instead part of law enforcement, and announced that some of its patrol vessels may be similarly armed.