Livy: On the Roman Method of Declaring War (Book 1.32)
Inasmuch as Numa [the second king of Rome] had instituted the religious rites for days of peace, Ancus Marcius [the fourth king of Rome] desired that the ceremonies relating to war might be transmitted by himself to future ages. Accordingly he borrowed from an ancient folk, the Aequicolae, the form which the [Roman] heralds still observe, when they make public demand for restitution. The [Roman] envoy when he comes to the frontier of the offending nation, covers his head with a woolen fillet, and says: Hear, O Jupiter, and hear ye lands _____ [i.e., of such and such a nation], let Justice hear! I am a public messenger of the Roman people. Justly and religiously I come, and let my words bear credit! Then he makes his demands, and follows with a solemn appeal to Jupiter. If I demand unjustly and impiously that these men and goods [in question] be given to me, the herald of the Roman people, then suffer me never to enjoy again my native country!
These words he repeats when he crosses the frontiers; he says them also to the first man he meets [on the way]; again when he passes the gate; again on entering the [foreigners'] market-place, some few words in the formula being changed. If the persons he demands are not surrendered after thirty days, he declares war, thus: Hear, O Jupiter and you too, JunoRomulus also, and all the celestial, terrestrial, and infernal gods! Give us ear! I call you to witness that this nation _____ is unjust, and has acted contrary to right. And as for us, we will consult thereon with our elders in our homeland, as to how we may obtain our rights.
After that the envoy returns to Rome to report, and the king was wont at once to consult with the Senators in some such words as these, Concerning such quarrels as to which the pater patratus [i.e., the head of the Roman heralds] of the Roman people has conferred with the pater patratus of the ____ people, and with that people themselves, touching what they ought to have surrendered or done and which things they have not surrendered nor done [as they ought]; speak forth, he said to the senator first questioned, what think you? Then the other said, I think that [our rights] should be demanded by a just and properly declared war, and for that I give my consent and vote. Next the others were asked in order, and when the majority of those present had reached an agreement, the war was resolved upon.
It was customary for the fetialis to carry in his hand a javelin pointed with steel, or burnt at the end and dipped in blood. This he took to the confines of the enemy's country, and in the presence of at least three persons of adult years, he spoke thus: Forasmuch as the state of the _____ has offended against the Roman People, the Quirites; and forasmuch as the Roman People the Quirites have ordered that there should be war with _____ and the Senate of the Roman People has duly voted that war should be made upon the enemy _____ : I, acting for the Roman People, declare and make actual war upon the enemy!
So saying he flung the spear within the hostile confines. After this manner restitution was at that time demanded from the Latins [by Ancus Marcius] and war proclaimed; and the usage then established was adopted by posterity.
The death of Numa was followed by a second interregnum. Then Tullus Hostilius, a grandson of the Hostilius who had fought so brilliantly at the foot of the Citadel against the Sabines, was chosen king by the people, and their choice was confirmed by the senate. He was not only unlike the last king, but he was a man of more warlike spirit even than Romulus, and his ambition was kindled by his own youthful energy and by the glorious achievements of his grandfather. Convinced that the vigour of the State was becoming enfeebled through inaction, he looked all round for a pretext for getting up a war. It so happened that Roman peasants were at that time in the habit of carrying off plunder from the Alban territory, and the Albans from Roman territory. Gaius Cluilius was at the time ruling in Alba. Both parties sent envoys almost simultaneously to seek redress. Tullus had told his ambassadors to lose no time in carrying out their instructions; he was fully aware that the Albans would refuse satisfaction, and so a just ground would exist for proclaiming war. The Alban envoys proceeded in a more leisurely fashion. Tullus received them with all courtesy and entertained them sumptuously. Meantime the Romans had preferred their demands, and on the Alban governor's refusal had declared that war would begin in thirty days. When this was reported to Tullus, he granted the Albans an audience in which they were to state the object of their coming. Ignorant of all that had happened, they wasted time in explaining that it was with great reluctance that they would say anything which might displease Tullus, but they were bound by their instructions; they were come to demand redress, and if that were refused they were ordered to declare war. "Tell your king," replied Tullus, "that the king of Rome calls the gods to witness that whichever nation is the first to dismiss with ignominy the envoys who came to seek redress, upon that nation they will visit all the sufferings of this war."