Did relations improve after that?
Somewhat. The U.S. never invaded Canada again, and the border was largely demilitarized in successive treaties between Britain and the U.S. But disputes over the border persisted throughout the early 19th century as the U.S. pushed westward. After the American Civil War, some Republicans demanded that Britain cede all of Canada as reparation for supporting the defeated Confederacy. Fears of another American invasion helped lead to the creation of the Dominion of Canada on July 1, 1867 — now celebrated as Canada Day — which united the colonies of Canada, New Brunswick, and Nova Scotia into one semi-autonomous confederation within the British Empire. It was the beginning of the modern Canadian nation.
https://theweek.com/articles/784421/brief-history-canadianamerican-relations