Why did the need for slaves drop during the 1800s

I would assume it has something to do with the 13th amendment since it abolished slavery

Fyi: 13th Amendment was passed in 1865

the results of roman expansion produced social conflict and civil war. julius caesar gained power and became a dictator but was then assassinated. the reign of augustus began a long period of imperial rule and peace in the roman empire. rome faced the problems of how to maintain peace, law, and order.

hope this !

brainliest?

b. the 200th birthday of the united states