In the early 1860s , a Texas racist could buy good cotton land for $6 an acre - a big half section of 320 acres went for $2000 ------ about the same price as ONE top quality (young skilled healthy) slave.
Needless to say, in this age before modernity's machinery, you needed far more than one such field hand to work all those acres.
So the prudent kept their slaves as healthy as they could , for as long as they could.
Because most of the South's wealth was in human being slaves, not in land, buildings or machinery.
But when the Nazi racists invaded Russia in 1941 they saw it not as a land of milk and honey but as a land of machinery : all oil refineries and tractor factories , with no need at all for enslaved Slavs .
The Slavs were all to be starved to death as superfluous to needs, under the infamous Hunger Plan.
Because the Era of Modernity was greatly opposed to human slavery --- as far too expensive and far too inefficient --- at least as compared to enslaving iron and petroleum.
This opposition to human slavery was called 'Progress.'
But in the end , the Nazi racists' best known machines - their 'big iron' panzers - ran out of petroleum and so once again slaves (teams of enslaved farm oxen) were called forth - to haul them into battle ....