Here's the passage in question:
"If your cavalry is not equal to the enemy's it is proper, after the ancient custom, to intermingle it with light infantry armed with small shields and trained to this kind of service. By observing this method, even though the flower of the enemy's cavalry should attack you, they will never be able to cope with this mixed disposition."
I'm not sure if this means "the youthful people of" the cavalry, as the phrase 'the flower of' seems to mean in other parts of De Re Militari, or "the greatest of their cavalry," or if this is a historically-used technical term for a particular part of the cavalry, like the front end or something.
Thanks for any replies!
'Flower' has the meaning of 'best' or 'most excellent'.
This use of the word was perhaps more common in the past then now, but it is still used, as witness the Scottish Rugby song Flower of Scotland, written in 1967.
https://en.wikipedia.org/wiki/Flower_of_Scotland
Here is the definition of "Flower" from the Online Etymology Dictionary:
flower (v.) 1200, "be vigorous, prosper, thrive," from flower (n.). Of a plant or bud, "to blossom," c. 1300. Meaning "adorn or cover with flowers" is from 1570s. Related: Flowered; flowering. flower (n.)
flower (n.) 1200, flour, also flur, flor, floer, floyer, flowre, "the blossom of a plant; a flowering plant," from Old French flor "flower, blossom; heyday, prime; fine flour; elite; innocence, virginity" (12c., Modern French fleur), from Latin florem (nominative flos) "flower" (source of Italian fiore, Spanish flor; compare flora).
From late 14c. in English as "blossoming time," also, figuratively, "prime of life, height of one's glory or prosperity, state of anything that may be likened to the flowering state of a plant.
" As "the best, the most excellent; the best of its class or kind; embodiment of an ideal," early 13c. (of persons, mid-13c. of things); for example flour of milk "cream" (early 14c.); especially "wheat meal after bran and other coarse elements have been removed, the best part of wheat" (mid-13c.). Modern spelling and full differentiation from flour (n.) is from late 14c.
In the "blossom of a plant" sense it ousted its Old English cognate blostm (see blossom (n.)). Also used from Middle English as a symbol of transitoriness (early 14c.); "a beautiful woman" (c. 1300); "virginity" (early 14c.). Flower-box is from 1818. Flower-arrangement is from 1873. Flower child "gentle hippie" is from 1967.
Just looked at the Latin, and pretty sure this is the line in question: "A fortioribus namque equitibus peditum protegenda sunt latera et a uelocioribus atque expeditis hostium cornua superfundenda atque turbanda."
A quick and dirty translation of it is basically: "For with the foot, they are shielded/defended from stronger cavalry at the flank and with the swifter infantry [lightly burdened troops], the greatest of the enemy wing/horn cannot break their line of battle."
Call it the translator taking a bit of artistic liberty with his flowery words :)