what was the only war fought between us and canada
Answer by Izak Deptuck. Confidence votes 9. US declared war in 1812 against Canada (which were part of the British Empire at the time) and tried to invade Canada making it their own but Canada held their own and defeated the US in the only war that the US has lost.onfidence votes 9. US declared war in 1812 against Canada (which were part of the British Empire at the time) and tried to invade Canada making it their own but Canada held their own and defeated the US in the only war that the US has lost.