The answer is: whether slavery would expand across the United States,
Manifest destiny Refers to the view that United States was destined by Gods to conquer all the territories in the north american continent.
This view originated from the southern colonies in mid 1800s. At that time, people worried that this view could lead to military expansion on northern states and expand the practice of slavery to these areas.
The disagreement for land ownership in the colonies and the control of the fur trade in the colonies were two factors that resulted in war between Britain and France.
