There were multiple reasons the War of 1812 happened, one of them being that Britain and France were battling, which caused Britain to restrict French trade from the United States, which didn't make Americans happy. Another reason was the United Kingdom didn't want the United States to expand and become powerful, as they may be deemed as a threat, so they supported Natives in keeping their land so Americans couldn't expand. The last reason I know of, was Britain would capture some of our troops and force them to join their army. These things lead to the War of 1812, which was followed by peace between the United Kingdom and the United States.