The causes of the American declaration of war against Great Britain on June 18, 1812 related to events far removed from Upper Canada geographically. Geography, however, determined that Upper Canada would be the primary battleground of the war. The long conflict between Britain and France from the French Revolution through the reign of Napoleon was fought to a great extent as an economic war. Britain and France attempted to interfere with the trade of neutrals, including the United States, that was deemed to benefit the enemy. .

             Britain issued Orders-in-Council which forbade trade through European ports under French control while France issued the Milan Decrees which outlawed trade with Britain. The trade dispute with Britain was heightened by the policy of stopping American vessels and removing any crew members believed to be deserters from the Royal Navy. Further, there were several naval incidents in the decade before 1812 which brought the two countries near war. .

             But there were also factors closer to home that contributed to the outbreak of hostilities:The expansion of American settlement in the "Old North-west" (today's Ohio, Michigan, Illinois), frequently in violation of treaties with the First Nations, led to ongoing conflict. The United States claimed that the Indian Agents at the British posts in the upper lakes were encouraging the resistance and supplying the means to carry it out. .

             Many American politicians saw war with Great Britain as an opportunity to expand northward through the conquest of Upper Canada. The American declaration of war in June 1812 followed a long period of grievance against Great Britain, but had no one particular cause.The United States, enraged by Great Britain's attitude, and determined to seize aboriginal land that was impeding their westward expansion, declared war on Great Britain and attacked its colony: Canada.

             At the turn of the 19th century, Europe became a vast battlefield with the eruption of the Napoleonic wars.