This quotation appears
It is marked as misattributed on wikiquote (where its original attestation seems to be Gabriel Suarez’s The Tactical Rifle, which assigns it to a certain Hericletus [sic]); Reddit has also marked it as a misquotation, although it assigns it to the apocryphal “Cynic Epistles” which were attributed to Heraclitus (this text is not available online as far as I can find; I have ordered it).
It is disturbing how popular this is as a meme: you can find it on quotefancy, pinterest, and way too many other places (it is of particular importance on sites that glorify firearms and snipers). Oh, it has also made the leap to popular history books, appearing in Paul B Bardunias’ and Fred Ray’s “Hoplites at War.”
To anyone who has read any of the extant fragments from Heraclitus, this is clearly not even remotely his style (here’s a cool site where you can find his fragments in Greek and translation). While it may be a bit too much to expect the internet to be familiar with Heraclitean obscurity, this passage sounds thoroughly and depressingly modern. It is not, of course, out of the character of Greek poetry to idolize a promakhos (the person who fights in front for his community), but phrasing and the “bring the others back” denouement is against the basic aesthetics of Greek martial poetry (see, for example, Callinus or Tyrtaeus). Of course, since all we have from Heraclitus is fragmentary, we are, as it were, in the dark.
Here’s one fragment that might work as inspiration:
Fr. 49 (103)
“One person is ten thousand to me, if he is the best.”
Εἷς ἐμοὶ μύριοι, ἐὰν ἄριστος ᾖ.
And here are a few more if we are looking for bellicose Pre-socratic quotations:
Fr. 53 (44)
“War is father and king of everything. War proves some to be gods and others human beings; it makes some slaves and others free.”
Πόλεμος πάντων μὲν πατήρ ἐστι πάντων δὲ βασιλεύς, καὶ τοὺς μὲν θεοὺς ἔδειξε τοὺς δὲ ἀνθρώπους, τοὺς μὲν δούλους ἐποίησε τοὺς δὲ ἐλευθέρους.
Fr. 80 (72)
“One must know that war is common, that justice is strife, and that all things happen through strife by necessity”
εἰδέναι δὲ χρὴ τὸν πόλεμον ἐόντα ξυνόν, καὶ δίκην ἔριν, καὶ γινόμενα πάντα κατ’ ἔριν καὶ χρεών.
The text is problematic here, another version: Εἰδέναι χρὴ τὸν πόλεμον ἐόντα ξυνόν, καὶ δίκην ἔριν· καὶ γινόμενα πάντα κατ᾿ ἔριν καὶ †χρεώμενα†.
Fr. 48 (66)
“The bow’s name is life but its work is death.”
Τοῦ βιοῦ οὔνομα βίος, ἔργον δὲ θάνατος.
This version keeps the wordplay between biós (“bow”) and bíos (“life”). Another version obscures this punning:
βίος: τῶι οὖν τόξωι ὄνομα βίος, ἔργον δὲ θάνατος.