An increase in life expectancy
If this is what I'm thinking then it's like Japan's history. Where Japan was basically run by feudal lords and their loyal clans. until Japan started to becomes westernized. It's affects where a civil war between the samurai fighting for the old ways and the new Japan military who were fighting for railroads and a new age that would disgrace the samurai's life style.
The nation needed workers so they could make money and slaves were the answer
We can tell day and nigth pretty much almost anywhere like libarys,houses,schools etc
