“They were brave and splendid, all the men. They died like brave men.”

Les hommes valeureux le sont du premier coup.
Chimène, act II, scene iii.
Le Cid (1636)

As quoted by Macrobius in Saturnalia, Book VI, Chapter I

The origin of this quote is often misattributed to Cicero; however, it is from Line 135-136 of Book 2, Satire 2 by Horace, "Quocirca vivite fortes, fortiaque adversis opponite pectora rebus." The English translation that most closely matches the one misrepresented as Cicero's is from a collection of Horace's prose written by E. C. Wickham, "So live, my boys, as brave men; and if fortune is adverse, front its blows with brave hearts."
Misattributed

William Cowper Prime in The Old House by the River (1853); first misattributed to Hawthorne in Notable Thoughts about Women: A Literary Mosaic (1882) by Maturin Murray Ballou, p. 239
Misattributed

"We Call Them the Brave" (the title of this poem is also obviously meant to be read as its first line, though set apart)
The Poems of Marianne Moore (2003)

Book II, Satire II, Line 135-136 (trans. E. C. Wickham)
Satires (c. 35 BC and 30 BC)

Speech to the Third Army (1944)

A Plea for Captain John Brown (1859)
Context: I hear many condemn these men because they were so few. When were the good and the brave ever in a majority? Would you have had him wait till that time came? — till you and I came over to him? The very fact that he had no rabble or troop of hirelings about him would alone distinguish him from ordinary heroes. His company was small indeed, because few could be found worthy to pass muster. Each one who there laid down his life for the poor and oppressed was a picked man, culled out of many thousands, if not millions; apparently a man of principle, of rare courage, and devoted humanity; ready to sacrifice his life at any moment for the benefit of his fellow-man.

De Providentia (On Providence): cap. 5, line 9
Alternate translation: Fire is the test of gold; adversity, of strong men. (translator unknown).
Moral Essays