Hollar illustrates the key moment in Virgil’s Aeneid (19 CE) when Aeneas realized that he had reached the land where he would build a new city where Trojans would prosper. The chosen moment is when Aeneas and his crew bivouac in a forest clearing in Latium and dine on skimpy provisions. But when Aeneas’ son Ascanius says, “See, we devour the plates (large slices of bread made from wheat) which we fed,” Aeneas realizes that a prophecy is being fulfilled, and Aeneas knows that this is where he will build a city worthy of his Trojan ancestry; what remains is to conquer Latium.

Virgil describes the scene with familiar picnic elements though the men are bivouacking. John Dryden’s translation of this passage in his The Aeneid (1697) gives a proper account of  Virgil’s details:
Beneath a shady tree, the hero spread
His table on the turf, with cakes of bread;
And, with his chiefs, on forest fruits he fed.
They sate; and, (not without the god’s command)
Their homely fare dispatch’d, the hungry band
Invade their trenchers next, and soon devour,
To mend the scanty meal, their cakes of flour.
  (VII: 104-110).

Thirty earlier in 1654, Wenceslaus Hollar illustrated the episode in John Ogilvy’s translation and contrived the bivouac as a picnic, then an unknown word. perhaps the scene was conceived as a  merenda, a Latin word denoting a light meal. John Florio’s influential English-Italian dictionary, A World of Words (1611), explains that it is a “repast between dinner and supper.”

See Richard Pennington. A Descriptive Catalogue of the Etched Work of Wenceslaus Hollar 1607-1677. Cambridge: Cambridge University Press, 1982; Virgil http://www.gpc.edu/~shale/humanities/literature/world_literature/virgil.html; and http://vergil.classics.upenn.edu/project.html#images;  Francis Cleyn and Wenceslaus Hollar’s. The Trojans’ First Meal in Latium (1654), translated by John Ogilvy. London, 1654. See: Univ. of Toronto Hollar digital library; http://link.library.utoronto.ca/hollar/digobject.cfm?Idno=Hollar_k_0333&query=Hollar_k_0333&size=large&type=browse