Divide and rule:
Elements of this technique involve:

creating or encouraging divisions among the subjects to prevent alliances that could challenge the sovereign
aiding and promoting those who are willing to cooperate with the sovereign
fostering distrust and enmity between local rulers
encouraging meaningless expenditures that reduce the capability for political and military spending

The goal is either to pit the lower classes against themselves to prevent a revolution, or to provide a desired solution to the growing discord that strengthens the power of the elites. It was heavily used by British Empire in India and elsewhere.

Alliances with various parties played a role in the Nazi Machtergreifung and Gleichschaltung, the seizure and consolidation of total power by the National Socialist German Workers Party. The Enabling Act, which gave the government the right of lawmaking, was supported by the Nazis' coalition partner, the German National People's Party, as well as by the Centre Party. Several months later, all political parties in Germany were banned except for the NSDAP.
The British Empire urged the Britons in British Cyprus to stir up the Turkish minority in order to neutralize agitation from the Greeks[23][24] The British colonial policy of “divide and rule” intentionally cultivated animosity between the Greek majority and the Turkish minority (18% of the population) in the island that remains divided till today.[25] A similar theme played out in Sri Lanka, where the British placed Sri Lankan Tamils (a local minority) in positions of power over the majority Sinhalese. This contributed to ethnic tension and ultimately violence, most notably in Black July.


https://en.wikipedia.org/wiki/Mount_Sinai_Hospital_(Manhattan)

https://en.wikipedia.org/wiki/Phillips_School_of_Nursing_at_Mount_Sinai_Beth_Israel