Do the brave deserve the fair?

The sentence is:

None but the brave _________ the fair.

Where the blank is to filled with deserve or deserves. My understanding is that it should be filled with deserve since the sentence here refers to more than one person i.e. many brave people and not just one, so it’s it in the plural form, and hence, we should use deserve.
But I am confused as more than half of the children in my class are using deserves.

Also, I checked the internet and found this article using deserves but the free dictionary using deserve.

Can someone please clarify my doubts on this one.

Thanks a lot.

Answer

As J.R. says, singular or plural deserve will work equally well. The bare sentence may be parsed as either:

Only brave men deserve fair women.
Only a brave man deserves a fair woman.

There is, however, an overriding consideration. This line is a quotation from a poem by John Dryden, Alexander’s Feast; or, the Power of Music.

‘Twas at the royal feast for Persia won
    By Philip’s warlike son—
  Aloft in awful state
  The godlike hero sate
    On his imperial throne;
  His valiant peers were placed around,
Their brows with roses and with myrtles bound
  (So should desert in arms be crown’d);
The lovely Thais by his side
Sate like a blooming Eastern bride
In flower of youth and beauty’s pride:—
  Happy, happy, happy pair!
    None but the brave
    None but the brave
  None but the brave deserves the fair!

Dryden wrote it singular, with ‘the brave’ referring specifically to Alexander and ‘the fair’ referring specifically to Thais.

ADDED:
In present-day English we no longer use the ADJECTIVE to refer to a single person except in epithets (e.g. Alexander the Great), only for classes of people. The singular therefore sounds odd to anyone who does not know the source of the line—which is probably 99% of the people who use it.

Attribution
Source : Link , Question Author : Gaurang Tandon , Answer Author : StoneyB on hiatus