Akey reason that the u. s. declared war on great britain in 1812 was

The War of 1812 was a conflict fought between the United States and the United Kingdom and their respective allies. Historians in Britain often see it as a minor theatre of the Napoleonic Wars; however, in the United States and Canada, it is seen as a war in its own right.

^^^ i agree with the person above me, good luck on whatever : )