“You're the soldier girl who tells the other troops who haven't fought the battle what it's like so they can fight it better.”

As quoted in The Complete Book of U.S. Presidents (1991) by William A. DeGregorio, p. 290

O’Connell recalling the spirited conduct of the Irish soldiers in Wellington’s army, at the Monster meeting held at Mullaghmast. Envoi, Taking Leave of Roy Foster, by Brendan Clifford and Julianne Herlihy, Aubane Historical Society, Cork.pg 16

As quoted in Honor Your Gifts (2007) by Dona M. Deane, p. 199.
Variant: But there is suffering in life, and there are defeats. No one can avoid them. But it's better to lose some of the battles in the struggles for your dreams than to be defeated without ever knowing what you're fighting for

Source: What I Saw At Shiloh (1881), I

Private Richard Sharpe to the Tippoo Sultan, p. 372
Sharpe (Novel Series), Sharpe's Tiger (1997)

Source: Lenovo Group’s Liu Chuanzhi on ‘Building a Healthy Company’ https://knowledge.wharton.upenn.edu/article/lenovo-groups-liu-chuanzhi-on-building-a-healthy-company/ in Knowledge @ Wharton (8 July 2009)

The Art of Poetry on a New Plan (1761), vol. ii. p. 147.
The saying "he who fights and runs away may live to fight another day" dates at least as far back as Menander (ca. 341–290 B.C.), Gnomai Monostichoi, aphorism #45: ἀνήρ ὁ ϕɛύγων καὶ ράλίν μαχήɛṯαί (a man who flees will fight again). The Attic Nights (book 17, ch. 21) of Aulus Gellius (ca. 125–180 A.D.) indicates it was already widespread in the second century: "...the orator Demosthenes sought safety in flight from the battlefield, and when he was bitterly taunted with his flight, he jestingly replied in the well-known verse: The man who runs away will fight again".