分而治之
a way of keeping yourself in a position of power by causing disagreements among other people so that they are unable to oppose you
It's just a fact that the principle that underpins any empire is divide and rule.
He was accused of trying to divide and rule.
That policy of divide and rule would seem to have backfired.
She actively encouraged conflict. Divide and rule, that was her motto.
It was universally acknowledged that he operated a system of divide and rule.
See also: divide verb (DISAGREE)