Divide and rule (Latin: divide et impera), or divide and conquer, in politics and sociology is gaining and maintaining power by breaking up larger concentrations of power into pieces that individually have less power than the one implementing the strategy. The use of this technique is meant to empower the sovereign to control subjects, populations, or factions of different interests, who collectively might be able to oppose its rule. Niccolò Machiavelli identifies a similar application to military strategy, advising in Book VI of The Art of War (1521) (L'arte della guerra): a Captain should endeavor with every act to divide the forces of the enemy. Machiavelli advises that this act should be achieved either by making him suspicious of his men in whom he trusted, or by giving him cause that he has to separate his forces, and, because of this, become weaker. The maxim divide et impera has been attributed to Philip II of Macedon. It was utilised by the Roman ruler Julius Caesar and the French emperor Napoleon (together with the maxim divide ut regnes). The strategy, but not the phrase, applies in many ancient cases: the example of Aulus Gabinius exists, parting the Jewish nation into five conventions, reported by Flavius Josephus in Book I, 169–170 of The Jewish War (De bello Judaico). Strabo also reports in Geographica, 8.7.3 that the Achaean League was gradually dissolved when it became part of the Roman province of Macedonia, as the Romans treated the various states differently, wishing to preserve some and to destroy others. The strategy of division and rule has been attributed to sovereigns, ranging from Louis XI of France to the House of Habsburg. Edward Coke denounces it in Chapter I of the Fourth Part of the Institutes of the Lawes of England, reporting that when it was demanded by the Lords and Commons what might be a principal motive for them to have good success in Parliament, it was answered: "Eritis insuperabiles, si fueritis inseparabiles. Explosum est illud diverbium: Divide, & impera, cum radix & vertex imperii in obedientium consensu rata sunt." [You would be invincible if you were inseparable. This proverb, Divide and rule, has been rejected, since the root and the summit of authority are confirmed by the consent of the subjects.] In a minor variation, Sir Francis Bacon wrote the phrase "separa et impera" in a letter to James I of 15 February 1615. James Madison made this recommendation in a letter to Thomas Jefferson of 24 October 1787, which summarized the thesis of The Federalist#10: "Divide et impera, the reprobated axiom of tyranny, is under certain (some) qualifications, the only policy, by which a republic can be administered on just principles." In Perpetual Peace: A Philosophical Sketch by Immanuel Kant (1795), Appendix one, Divide et impera is the third of three political maxims, the others being Fac et excusa (Act now, and make excuses later) and Si fecisti, nega (If you commit a crime, deny it). Elements of this technique involve: Historically, this strategy was used in many different ways by empires seeking to expand their territories. Immanuel Kant was an advocate of this tactic, noting that "the problem of setting up a state can be solved even by a nation of devils" so long as they possess an appropriate constitution which pits opposing factions against each other with a system of checks and balances. The concept is also mentioned as a strategy for market action in economics to get the most out of the players in a competitive market.
Divide and rule can be used by states to weaken enemy military alliances. This usually happens when propaganda is disseminated within the enemy states in an attempt to raise doubts about the alliance. Once the alliance weakens or dissolves, a vacuum will allow the state to achieve military dominance.
In politics, the concept refers to a strategy that breaks up existing power structures, and especially prevents smaller power groups from linking up, causing rivalries and fomenting discord among the people to prevent a rebellion against the elites or the people implementing the strategy. 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.
The principle "divide et impera" is cited as a common in politics by Traiano Boccalini in La bilancia politica.
In families where one or both parents shows traits of Narcissistic Personality Disorder (NDP), they will attempt control of their children through a technique akin to political divide et impera by pitting child against child in a struggle for their affection. A common practice by the narcissistic parent is to designate a 'golden-child' who receives praise and can do no wrong, and a 'scape-goat' who gets the blame for everything that goes wrong, but this is used by the narcissist to further divide them by keeping both children in a state of insecurity about their positions in the family. In their battle to receive the limited supply of approval from the parent, they will see each other as a threat, and the parent can assume the role of saviour when they intervene to calm the aggression they created.
Clive R. Boddy found that "divide and conquer" was a common strategy by corporate psychopaths used as a smokescreen to help consolidate and advance their grip on power in the corporate hierarchy.
During the period of Nigeria being under colonial rule from 1900 to 1960, different regions were frequently reclassified for administrative purposes. The resulting tensions between Nigerian ethnic groups such as the Igbo and Hausa made it easier for the colonial authorities to consolidate their power in the region.
While the Mongols imported Central Asian Muslims to serve as administrators in China, the Mongols also sent Han Chinese and Khitans from China to serve as administrators over the Muslim population in Bukhara in Central Asia, using foreigners to curtail the power of the local peoples of both lands.
Some Indians historians, such as politician Shashi Tharoor, assert that the British Raj frequently used this tactic to consolidate their rule and prevent the emergence of the Indian independence movement. A Times Literary Supplement review by British historian Jon Wilson suggests that although this was broadly the case a more nuanced approach might be closer to the facts. In the same vein, Indian jurist Markandey Katju wrote in The Nation:
Some analysts assert that the United States is practicing the strategy in the 21st-century Middle East through their supposed escalation of the Sunni–Shia conflict. British journalist Nafeez Ahmed cited a 2008 RAND Corporation study for the U.S Armed Forces which recommended "divide and rule" as a possible strategy against the Muslim world in "the Long War". British historian Christopher Davidson argues that the current crisis in Yemen is being "egged on" by the United States government, and could be part of a wider covert strategy to "spur fragmentation in Iran allies and allow Israel to be surrounded by weak states”.
The Ottoman Empire often used a divide-and-rule strategy, pitting Armenians and Kurds against each other. This strategy no longer worked in the Republic of Turkey because the Armenians were eliminated in the Armenian Genocide.
Harry G. Broadman opined in Forbes regarding President Donald Trump: "[a]s in his campaign, the President has been successfully—at least to date—pursuing a divide and conquer strategy domestically and internationally to try to achieve his goals. The result is an absence of a robust set of checks and balances to ensure that the best economic interests of the U.S. and the world will be served."