Divide and Govern
Divide a nation into parties, or set your enemies at loggerheads, and you can have your own way. A maxim of Machiavelli, a noted political writer of Florence (1469-1527).
“Every city or house divided against itself shall not stand.” —Matthew xii. 25.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894