> Didn't America attack british colonies in Canada in 1812?
Yes.
> I thought America was the aggressor in that war and Britain just retaliated.
It's more complicated than that. Britain tried to prohibit America from trading with France, as part of their war against Napoleon. America thought that was against international law. Britain also had a habit of seizing sailors off of American ships and forcing them into service in the Royal Navy, which the US regarded as extremely over the line. The British were also (pre-war, IIUC) arming Native Americans on the US western frontier.
Eventually, the US declared war. But I'm not sure that makes them the aggressor, at least not 100%...
Yes.
> I thought America was the aggressor in that war and Britain just retaliated.
It's more complicated than that. Britain tried to prohibit America from trading with France, as part of their war against Napoleon. America thought that was against international law. Britain also had a habit of seizing sailors off of American ships and forcing them into service in the Royal Navy, which the US regarded as extremely over the line. The British were also (pre-war, IIUC) arming Native Americans on the US western frontier.
Eventually, the US declared war. But I'm not sure that makes them the aggressor, at least not 100%...