Answer:
American invaders moved into the Mexican Territory to fight and also claim some area of land which were at the borders of the two countries. Texas was annexed to the United States and they wanted more of Mexican lands.
The Anglo-Saxons saw themselves as Superior to others and believed that they were destined to spread across other countries and continents. They used this belief to justify the war they had with the Mexicans.
The Mexican-American War was controversial between the North and the South due to the addition of other states which would alter the balance between the North and South.