Separation from a main group to form a new group as a result of disunity is called

Segregation

Explanation:

Segregation is the process of dissociation whereby individuals and groups lose physical and social contact with other individuals and groups. This social and physical separation or distance comes from biological and social factors such as race, wealth, education, religion, profession, nationality, etc. In other words, we might call segregation a situation where the separation of a main group occurs to form a new group as a result of disunity.

the american revolution was by the middle and upper class, and the french was by the lower and middle class.

in griswold v. connecticut (1965), the supreme court ruled that a state's ban on the use of contraceptives violated the right to marital privacy.