Answer:
Mexican American war
Step-by-step explanation:
The Mexican American war was ended with the Treaty of Guadalupe Hidalgo.
Part of this treaty included the Mexican Cession, which would be granted from Mexico to the US due to their victory
It included modern day states such as Arizona, California, New Mexico, and others.
However, with so many states being added from the Mexican Cession, the issue of slavery came up again.
The Compromise of 1850 was created to try to balance free and slave states in the new territory.