DE MONARCHIA OF DANTE ALIGHIERI
CHAPTER XI: The single combats of the Roman people.
1. That the Roman people acquired Empire by single combat is confirmed by witnesses worthy of belief: In citing witnesses, not only shall we prove this, but we shall show that, from the founding of the Roman Empire, the decision of all questions whatsoever was reached through contests of man to man.
2.. At the very outset, when contention arose in regard to the colonization of Italy by father Aeneas, who was first parent of the Roman people, and Turnus, king of the Rutilians, stood out against him; finally, as is sung in the last book of the Aeneid, both kings agreed to seek the good pleasure of God in a combat singly between themselves.  The closing verses of our Poet testify how great was the clemency of Aeneas, victor in the contest, and how as vanquisher he would have bestowed life and peace at one time on the vanquished, had he not espied on Turnus the belt stripped by him from Pallas slain. 
3. And when two peoples, the Romans and Albanians, had grown up in Italy from the same Trojan root, and when they had long striven for the ensign of the eagle, the household gods of the Trojans, and the honor of supreme command, at length with mutual consent they determined the question by a combat between the three Horatian and the three Curiatian brethren, in the view of the kings and people waiting anxiously on either side. The three champions of the Albanians and two of the Romans fell, and the victory went to the Romans, in the reign of Hostilius. And to this, which Livy narrates in detail in his first book,  Orosius also bears witness. 
4. Livy tells that they then strove for Empire with their neighbors, Sabines and Samnites, observing every rule of war, and preserving the characteristics of contests man to man, although the contestants were a multitude. During the struggle carried on in this wise with the Samnites, Fortune seemed, as it were, almost to repent of her undertaking. And this Lucan uses as an example in his second book, saying: "Or how many heaps of slain choked up the Colline Gate, what time the headship of the world and authority in earthly things were well-nigh transferred to other realms, and the Samnites overtopped the Caudine Forks with Roman dead." 
5. After these troubles with Italy were quieted, but the decree of God was not yet certain in regard to the Greeks and the Phoenicians aspiring to Empire, Fabricius for the Romans and Pyrrhus for the Greeks contended with a multitude of soldiery for the glory of sovereignty, and Rome was triumphant. Then Scipio  for the Italians and Hannibal for the Africans did battle in the form of single combat, and Africa succumbed to Italy, as Livy and other writers of Roman affairs endeavor to show.
6. Who is then so dull of wit he fails to see that this splendid people gained the crown of a world-wide realm by right of single combat? Verily, a Roman might say with the Apostle addressing Timothy, "There is laid up for me a crown of righteousness"  -- that is to say, laid up in the eternal providence of God. Now let presumptuous jurists behold how far they stand beneath that watch-tower of reason whence the human mind looks out upon these principles, and let them be silent, content to give counsel and judgment according to the import of the law.
7. And now the main proposition of the present book is proved, that the Roman people attained imperial power through single combat, and that therefore they attained it by Right.
8. Thus far the argument has progressed through reason based chiefly on rational principles, but from now on it shall be re-demonstrated through the principles of Christian faith. 
1. Aen. 12. 942.
2. Aen. 12. 948. Par. 6. 35: "Pallas died to give a kingdom to the Roman ensign," seeing that his death was the real cause of Turnus' death.
3. Liv. 1. 24, 25.
4. Oros. 2. 4. 9.
5. Phar. 2. 135-138: "Romanaque Samnis ultra Caudinas superavit vulnera furcas." Modern editions have "speravit" or "spiravit" instead of "superavit."
6. Par. 27. 61: "The Providence on high, which with Scipio guarded for Rome the glory of the world."
Par. 6. 49: "It [the ensign] brought to earth the pride of the Arabs, who in Hannibal's train passed the Alpine cliffs. ... Under it in their youth triumphed Scipio and Pompey. ... Afterward, hard upon the time when the heaven wholly willed to bring back the world to its tranquil order, Caesar by the will of Rome bare it."
7. 2 Tim. 4. 8.
8. De Mon. 2. 8. 1. For the chapter as a whole read as its best commentaries Par. 6 (Justinian to Dante) and Conv. 4. 5.