Answer:
Intergovernmental revenue
Under the treaty of the Guadalupe - Hidalgo , the Mexican American War ended in favor of the United States , this also relinquished the United States with 525,000 square miles of land from the Southern Border
American patriot soldiers were fighting against the stronger British soldiers with a stronger navy, better weapons, and more soldiers to fight. There wasn’t anything unfair, but the British had a leg up in the fight being the top of the top country in warfare.
America winning the war was a big upset for the British as they lost to their own territory.