What was the primary outcome of the War of 1812?

The primary outcome of the War of 1812 was the affirmation of American independence and the emergence of a strong sense of nationalism among U.S. citizens. Despite the war being fought largely against Great Britain, the U.S. was able to demonstrate its capacity to defend itself and maintain its sovereignty. The successful defense against British invasions, notably the defense of Fort McHenry, helped to inspire national pride and unity, evidenced by the writing of "The Star-Spangled Banner."

This newfound nationalism had lasting effects on American culture and politics, propelling the nation toward further expansion and the assertion of its identity separate from European influences. The war also served as a catalyst for the demise of the Federalist Party, which opposed the war, thus further solidifying the Democratic-Republican Party's dominance and shaping the political landscape of the nation.

In contrast, while territorial gains, increased tensions with Canada, and effects on U.S. foreign relations were factors during and after the war, they do not encapsulate the broader and more profound impact that the affirmation of independence and rising nationalism had on the nation as a whole.