Noah Webster
Parley
P'ARLEY, verb intransitive [Latin fero, or pario.] In a general sense, to speak with another; to discourse; but appropriately, to confer with on some point of mutual concern; to discuss orally; hence, to confer with an enemy; to treat with by words; as on an exchange of prisoners, on a cessation of arms, or the subject of peace.
P'ARLEY, noun Mutual discourse or conversation; discussion; but appropriately, a conference with an enemy in war.
We yield on parley but are storm'd in vain.
To beat a parley in military language, to beat a drum or sound a trumpet, as a signal for holding a conference with the enemy.