The war of 1812 was caused mainly by the clash of aspirations between the US and Great Britain -both wanted to become stronger, but United Kingdom did not want the US to become stronger and for example blocked its trade with France -in reply, the US declared war.
The war ended by a peace treaty signed by both countries, in which the UK, after some recent defeats, gave up its claims to territory in America, and which meant that the war would create no territorial changes.