According to the "Random House Dictionary of Popular Proverbs and Sayings":
Originally a Latin saying, "divide et impera" ("divide and rule"), the saying has been in common use since "M. Hurault's Discourse upon the Present state of France" (1588). . .
The Dictionary also cites its use by Machiavelli.
Also, the "Oxford English Dictionary" gives a definition:
a statement of the policy of not allowing subject peoples or factions to make common cause.
Says that "divide et impera" is sometimes translated as "divide and govern." It lists several usages beginning with 1602. It also lists a dictionary usage in 1870 from Brewer "Dictionay of Phrases and Fables":
"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."
The OED also lists a dictionary listing in 1948 from B. Stevenson "Home Book of Proverbs":
"Divide et impera" was the motto of Philip of Macedon and of Louis XI of France, in dealing with his nobles. It is the traditional motto of Austria. Polybius, Bossuet, and Monteesquieu used it, but it is generally ascribed to Machiavelli.
In contrast, James Morwood's "Dictionary of latin words and phrases" published in 1998 says:
"divide et impera" -- "divide and rule". The motto of Louis XI of France. Though this political axiom--conveying that government is more easily maintained if factions are set against each other and not permitted to unite against the ruler--is attributed to the Florentine political philosopher Niccolo Machiavelli (1469-1527), he in fact denounced it.
[and here are some usages in American literature]
In the next canvass, we shall be influenced by no party consideration, and no Carthagenian coalescence or collusion with our people will be suffered to effect, or operate against General Bennett,
or any other of our tried friends, already semi-officially in the field; so the partizans in this county, who expect to divide the friends of humanity and equal rights, will find themselves mistaken�we care not a fig for Whig or Democrat; they are both alike to us, but we shall go for our friends, our tried friends, and the cause of human liberty, which is the cause of God. We are aware that "divide and conquer" is the watchword with many, but with us it cannot be done�we love liberty too well�we have suffered too much to he easily duped�we have no catspaws amongst us.
STATE GUBERNATORIAL CONVENTION.
City of Nauvoo, Illinois, December 20th, A.D. 1841.
JOSEPH SMITH. Lieutenant-General of the Nauvoo Legion.
Times and Seasons - 6 Volumes ** ( 3:5:650 )
History of the L.D.S. Church - 7 volumes (4 - 479)
The idea of dividing the Territory up among the adjoining Territories is not
practicable now; under it, the Mormons, instead of being divided and
conquered, would divide and conquer; for, with their numbers and discipline,
they could out-vote and out-manage three territories.
Our New West - (Book on American West in 19th century) - Samuel Bowles
Hartford Publishing Co., Hartford, CT. J. D. Dennison, New York. J. A. Stoddard, Chicago, IL. 1869.