How did president johnson originally attempt to break up the southern aristocracy

he limited those who could take the loyalty oath to people who were low level confederate officials or had less than $20,000 in property

Explanation:

In the past, The southern states were ruled from the background by a group of wealthy plantation owners who benefited from slavery.

By putting the $20,000 limit, president Johnson wanted to ensure that none of these rich plantation owners able to became a part of the union (since they have much more than $20,000). He does not wanted the wealthy plantation owner to have further influence from the people and prevent them from initiating another conflict with the northern states.