Titus Livius (Livy), The History of Rome, Book 1
Benjamin Oliver Foster, Ph.D., Ed.

24. It chanced that there were in each of¹ these armies triplet brothers, not ill-matched either in age or in physical prowess. That they were Horatii and Curiatii is generally allowed, and scarcely any other ancient tradition is better known; yet, in spite of the celebrity of the affair, an uncertainty persists in regard to the names —to which people, that is, the Horatii belonged, and to which the Curiatii. The writers of history are divided. Still, the majority, I find, call the Roman brothers Horatii, and theirs is the opinion I incline to adopt. [2] To these young men the kings proposed a combat in which each should fight for his own city, the dominion to belong with that side where the victory should rest. [3] No objection was raised, and time and place were agreed on. Before proceeding with the battle, a treaty was made between the Romans and the Albans, providing that the nation whose citizens should triumph in this contest should hold undisputed sway over the other nation. One treaty differs from another in its terms, but the same procedure is always employed. [4] On the present occasion we are told that they did as follows, nor has tradition preserved the memory of any more ancient compact. The fetial² asked King Tullus, “Dost thou command me, King, to make a treaty with the pater patratus of the Alban People?” Being so commanded by the king, he said, “I demand of thee, King, the sacred herb.” [5] The king replied, “Thou shalt take it untainted.” The fetial brought from the citadel an untainted plant. After this he asked the king, “Dost thou grant me, King, with my emblems and my companions, the royal sanction, to [p. 85]speak for the Roman People of the Quirites?” [6] The³ king made answer, “So far as may be without prejudice to myself and the Roman People of the Quirites, I grant it.” The fetial was Marcus Valerius; he made Spurius Fusius pater patratus, touching his head and hair with the sacred sprig. The pater patratus is appointed to pronounce the oath, that is, to solemnize the pact; and this he accomplishes with many words, expressed in a long metrical formula which it is not worth while to quote. [7] The conditions being then recited, he cries, “Hear, Jupiter; hear, pater patratus of the Alban People: hear ye, People of Alba: From these terms, as they have been publicly rehearsed from beginning to end, without fraud, from these tablets, or this wax, and as they have been this day clearly understood, the Roman People will not be the first to depart. [8] If it shall first depart from them, by general consent, with malice aforethought, then on that day do thou, great Diespiter, so smite the Roman People as I shall here to-day smite this pig: and so much the harder smite them as thy power and thy strength are greater.” [9] When Spurius had said these words, he struck the pig with a flint. In like manner the Albans pronounced their own forms and their own oath, by the mouth of their own dictator and priests.