The War of 1812 

Due to disputes between the United States and Britain over impressment of US Soldiers to the British Navy and the naval blockade by Britain on Napoleonic France aswell as disputes over the Northern Territories in Canada, America declared war on Britain.
During the course of the 3-year war, America won a series of naval battles, although failing to make an impression into British territory on land due to British aggression. The most prominent of American victories being those at York (Toronto) and after the war had ended officially, at the battle of New Orleans. British forces invading America lost the battle of Baltimore and succeeded to burn Washington DC (which was saved by a heavy rainstorm).
The territory Britain did capture was handed back after the war, as were the gains of America...

What a stupid pointless conflict.
And what happened to the blockade on France? It continued! And Britain smashed the French Navy at the Battle of Trafalgar and pummeled Napoleon at Waterloo, with the help of the faithful Prussians. Thanks Germany, we know who our REAL friends are!

Just kidding, thankfully now Anglo-American relations are just peachy.

The War of 1812 by Stuart Fletcher November 2, 2004