Overview: John Green teaches you about the War of 1812. The War of 1812 was fought between the United States and its former colonial overlord England. It started in, you guessed it 1812. The war lasted until 1815, and it resolved very little. John will take you through the causes of the war, tell you a little bit about the fighting itself, and get into just why the US Army couldn't manage to make any progress invading Canada.