How did the fugitive slave act lead to sectionalism and the civil war?

To answer the question about how he fugitive slave act led to sectionalism and the civil war,

As a result of the previously established Fugitive Slave Act of 1793, the people were forced to pick sides; if they wanted slavery to end or not.

As a result of this, the South and the North became increasingly hostile which eventually led to the South breaking away and the Civil War.

monarchy doesn’t have to have the hereditary element. there have been elective monarchies in the past where you choose your king-for-life and when he dies elect someone else for the job.