The War of 1812 was a military conflict, lasting for two and a half years, fought by the United States of America against the United Kingdom of Great Britain and Ireland, its North American colonies, and its American Indian allies. Seen by the United States and Canada as a war in its own right, it is frequently seen in Europe as a theatre of the Napoleonic Wars, as it was caused by related issues to that war (especially the Continental System). The war resolved many issues which remained from the American Revolutionary War but involved no boundary changes. The United States declared war on June 18, 1812, for several reasons, including trade restrictions brought about by the British war with France, the impressment of US merchant sailors into the Royal Navy, British support for Native American tribes against European American expansion, outrage due to perceived insults to national honor because of the frequent stopping by the British west African Squadron of American slave ships carrying black slaves to the new world in open defiance of the trade slave ban of 1808, and possible US interest in annexing British territory.