Did Britons see the War of 1812 as a betrayal?

Was the claim that America stabbed Britain in the back by siding with Napoleon merely propaganda?

It also reflected a sincere British public view that the United States had attacked while Britain was fighting Napoleon, whom many Britons regarded as Europe's great enemy.

The description of America supporting Napoleon reflected a belief sincerely held by many Britons. In that view, the United States had attacked while Britain was fighting a ruler they regarded as a scourge of Europe. Calling the belief mere propaganda would miss how seriously contemporaries took it.