Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_5 ( ceased_to_be_duchess VARCHAR, became_duchess VARCHAR )

### Question ###
When did the duchess who became duchess on 7/8 April 1766 cease to be duchess?

### Accurate SQL ###

SELECT ceased_to_be_duchess FROM table_name_5 WHERE became_duchess = "7/8 april 1766"