Fetial

Nicomachus, as explained in the next line, was already known to the Elean priests or fetials, or whatever we are to call them, as a guest-friend.

It was customary for the fetial to carry to the bounds of the other nation a cornetwood spear, iron-pointed or hardened in the fire, and in the presence of not less than three grown men to say, "Whereas the tribes of the Ancient Latins and men of the Ancient Latins have been guilty of acts and offences against the Roman People of the Quirites; […] I therefore and the Roman People declare and make war on the tribes of the Ancient Latins and the men of the Ancient Latins." Having said this, he would hurl his spear into their territory.

After an insult had been offered Rome, or a wrong inflicted on it, several of the twenty sacred heralds, members of the College of Fecials, proceeded to demand reparation. […] [I]f war were decided, a second deputation of fecials was nominated upon whom was placed the symbolic duty of discharging a javelin into the enemy camp. This part of the procedure had obvious difficultes, and, after resorting to the fiction of performing it at an enemy camp in Rome, the fecials finally adopted an appropriate ceremony at the temple of Bellona. The fecials also had religious functions at the conclusion of a peace. It was the oath taken by the chief fecial which sanctified a treaty entered into with, or by, the Roman people.

[P]erhaps the shadowy fetials were never actually an independent priesthood but were senatorial priests assigned diplomatic functions. If fetials were originally senators, this would explain the parallel fetial and senatorial function in "international relations" and account for the continuity between fetials and later senatorial legates. Of the twenty patrician fetials, only four were customarily chosen to serve in an embassy.

According to authors of the late Republic, the fetials supervised Roman adherence to the iura belli, the laws of war. How, then, should we interpret the silence with respect to the fetials of Polybius, the central concern of whose history was Roman imperialism, but who mentions the fetials not even once?

Fetiales also investigated allies' claims of abuse by Romans; if substantiated, the fetiales delivered the men accused to the injured parties.

[P]erhaps the shadowy fetials were never actually an independent priesthood but were senatorial priests assigned diplomatic functions. If fetials were originally senators, this would explain the parallel fetial and senatorial function in "international relations" and account for the continuity between fetials and later senatorial legates.

The institution of a college of heralds and the fecial law, were proofs of a people considerably advanced in the cultivation of the law of nations as a science; and yet with what little attention they were accustomed to listen to the voice of justice and humanity, […]