With what European nation did the USnearly fight over?

The United States nearly fought with Great Britain over the Oregon Territory in the mid-19th century. The conflict arose from competing claims between the US and Britain, leading to heightened tensions and the slogan "54-40 or Fight!" in reference to the northern latitude line both nations claimed. Ultimately, the dispute was peacefully resolved with the Oregon Treaty of 1846, which established the boundary along the 49th parallel.