Answer:
to sanction a liberal constitution
Step-by-step explanation:
John VI took over Montevideo in Uruguay
This led to a conflict with Spain
John VI 's stay in Brazil made the Portuguese impatient for change.
In 1820 the radical revolution in Spain spread to Portugal
John VI agreed to leave Brazil
John VI started the process of creating a liberal constitution
John VI left leaving his heir Peter (Pedro) in Rio de Janeiro
John VI | King of Portugal | Britannica