An then the Overlords realise that a terrified populace is very unlikely to be inventive, creative, dilligent, striving or reliable and trustworthy and is even more unlikely to be willing to take up arms on behalf of the Overlords' interests, abroad and domestic.
So what do the Overlords do then?
A) Get themselves a new populace, not yet as terrorised and terrified into depression as the original one.
An then the Overlords realise that a terrified populace is very unlikely to be inventive, creative, dilligent, striving or reliable and trustworthy and is even more unlikely to be willing to take up arms on behalf of the Overlords' interests, abroad and domestic.
So what do the Overlords do then?
A) Get themselves a new populace, not yet as terrorised and terrified into depression as the original one.
Also A) Get themselves an Enemy to wage War upon.
Rinse and repeat.