What is the earliest known appearance of the phrase "All's fair in love and war"? Not the exact phrasing, but the sentiment?

A poster on another board claims, "The earliest source is from Chaucer in Troilus and Criseyde (c.1380)," but I have two problems with his view, which he does not support with any exact quote or secondary authority:

• I can't find it anywhere in Troilus. Nothing that I could recognize after a computer search on the original Middle-English text. Perhaps some of you can handle that language better than I.
  . . .(I couldn't find any free modern-English text, but did try the non-free ones in Amazon's search-inside-the-book feature. Nothing found there either.)
• Since many others expressed the sentiment after Chaucer, is it credible that that none of the Roman writers said it centuries before him?

This message has been edited. Last edited by: <wordnerd>,

I can't find proof right now, but I'd swear it's from Juvenal.

That would seem plausible, but I couldn't find it either. I found this list of Juvenal's quotes. I wonder what is so intolerable about a wealthy woman.