Histories
Herodotus
Herodotus. Godley, Alfred Denis, translator. Cambridge, MA; London: Harvard University Press; William Heinemann, Ltd., 1920-1925 (printing).
The Argives came out to save their territory from being cut off, then after debate the two armies agreed that three hundred of each side should fight, and whichever party won would possess the land. The rest of each army was to go away to its own country and not be present at the battle, since, if the armies remained on the field, the men of either party might render assistance to their comrades if they saw them losing.