Not a Virginia class as I incorrectly surmised, but a modified Los Angeles class submarine - thanks Peterz - USS Boise was our visitor over the past few days. The sub, SSN 764, and recent winner of the Brandenburg cup as best ship in the Atlantic fleet, was in port in part to commemorate the United States' Memorial Day.
Halifax was an important port during the war of 1812-1814 (which we won no matter what anyone says) and there are many graves here of US war dead from that conflict. They died during the North American version of the war, which was started when Britain was distracted by Napoleon. It was the US intention to take over the British North American colonies (which now form part of Canada.) They did not succeed.
USS Boise sailed this afternoon. It does look somewhat battered, but apparently unbowed.