There were many reasons for Great Britain and the United States to start the War of 1812.

The War of 1812 was the result of increasing tensions and global political conflicts between the United State and the United Kingdom. In the first ten years of the 19th century, the American merchant marine had doubled, and British citizens really feared that American merchant ships may overtake them. As part of their conflict with France in 1807, Britain imposed trade restrictions that forbade neutral nations from doing business with France. This was viewed by the United States as a flagrant violation of international trade law that was directed deliberately at the expanding American economy. The British actively captured American ships and sailors in addition to limiting American trade. Known as impressment, Britain has been kidnapping American troops for years and forcing them to join the royal navy.

The conflict that contributed to the start of the War of 1812 was also a conflict of manifest destiny. The British supported Native American tribes in the Northwest Territory, at the same time many Americans wanted to expand westward. Madison’s predecessor, Thomas Jefferson, had instilled within the American populous that the continent was theirs for the taking. For the many reasons above, both countries decided to start a war that they couldn't avoid. Both America and the United Kingdom went to war despite not being fully prepared.