=Bev17243;9001136]I know that Papal Infallibility was defined by the Vatican Council I 1869.
The reason for this was that it was not an issue before then
The Early Church Fathers understood from the beginning that Peter and his successors held a place of primacy in the Church.
Clement of Rome
Accept our counsel and you will have nothing to regret. . . . If anyone disobeys the things which have been said by him [Jesus] through us, let them know that they will involve themselves in no small danger. We, however, shall be innocent of this sin and will pray with entreaty and supplication that the Creator of all may keep unharmed the number of his elect (Letter to the Corinthians 58:2, 59:1[A.D. 95]).
Ignatius of Antioch
You [the See of Rome] have envied no one, but others have you taught. I desire only that what you have enjoined in your instructions may remain in force (Epistle to the Romans 3:1 [A.D. 110]).
But since it would be too long to enumerate in such a volume as this the succession of all the churches, we shall confound all those who, in whatever manner, whether through self-satisfaction or vainglory, or through blindness and wicked opinion, assemble other than where it is proper, by pointing out here the successions of the bishops of the greatest and most ancient church known to all, founded and organized at Rome by the two most glorious apostles. Peter and Paul, that church which has the tradition and the faith which comes down to us after having been announced to men by the apostles. With that church, because of its superior origin, all the churches must agree, that is, all the faithful in the whole world, and it is in her that the faithful everywhere have maintained the apostolic tradition (Against Heresies 3:3:2 [inter A.D. 180-190]).
Clement of Alexandria
[T]he blessed Peter, the chosen, the preeminent, the first among the disciples, for whom alone with himself the Savior paid the tribute [Matt. 17:27], quickly grasped and understood their meaning. And what does he say? "Behold, we have left all and have followed you" [Matt. 19:2 7, Mark 10:28] (Who is the Rich Man That is Saved? 21:3-5 [A.D. 200]).
[T]he Lord said to Peter, "On this rock I will build my Church, I have given you the keys of the kingdom of heaven [and] whatever you shall have bound or loosed on earth will be bound or loosed in heaven" [Matt. 16:18-19]. ... Upon you, he says, I will build my Church; and I will give to you the keys, not to the Church; and whatever you shall have bound or you shall have loose and, (Modesty 21:9-10 [A.D. 220]).
Letter of Clement to James
Be it known to you, my lord, that Simon [Peter], who, for the sake of the true faith, and the most sure foundation of his doctrine, was set apart to be the foundation of the Church, and for this end was by Jesus himself, with his truthful mouth, named Peter, the first-fruits of our Lord, the first of the apostles; to whom first the Father revealed the Son; whom the Christ, with good reason, blessed; the called, and elect [A.D, 221]).
With a false bishop appointed for themselves by heretics, they dare even to set sail and carry letters from schismatics and blasphemers to the Chair of Peter and to the principal church [at Rome], in which sacerdotal unity has its source" (Epistle to Cornelius [Bishop of Rome] 59:14 [A.D. 252]).
The Lord says to Peter: "I say to you," he says, "that you are Peter, and upon this rock I will build my Church" . . . On him he builds the Church, and to him he gives the command to feed the sheep John 21:17], and although he assigns a like power to all the apostles, yet he founded a single chair [cathedra], and he established by his own authority a source and an intrinsic reason for that unity. Indeed, the others were that also which Peter was [i.e., apostles], but a primacy is given to Peter, whereby it is made clear that there is but one Church and one chair. So too, all [the apostles] are shepherds, and the flock is shown to be one, fed by all the apostles in single-minded accord. If someone does not hold fast to this unity of Peter, can he imagine that he still holds the faith? If he [should] desert the chair of Peter upon whom the Church was built, can he still be confident that he is in the Church? (The Unity of the Catholic Church 4 [A.D. 251]).
Cyril of Jerusalem
In the power of the same Holy Spirit, Peter, both the chief of the apostles and the keeper of the keys of the kingdom of heaven, in the name of Christ healed Aeneas the paralytic at Lydda, which is now called Diospolis [Acts 9 ;3 2-3 4] (Catechetical Lectures 17;27 [A.D. 350]).
In the city of Rome the Episcopal chair was given first to Peter, the chair in which Peter sat, the same who was head — that is why he is also called Cephas — of all the apostles, the one chair in which unity is maintained by all. Neither do the apostles proceed individually on their own, and anyone who would [presume to] set up another chair in opposition to that single chair would, by that very fact, be a schismatic and a sinner. . . . Recall, then, the origins of your chair, those of you who wish to claim for yourselves the title of holy Church" (The Schism of the Donatists 2:2 [circa A.D. 367]).
Ambrose of Milan
[Christ] made answer: "You are Peter, and upon this rock will I build my Church . . ." Could he not, then, strengthen the faith of the man to whom, acting on his own authority, he gave the kingdom, whom he called the rock, thereby declaring him to be the foundation of the Church [Matt. 16:18]? (The Faith 4:5 [A.D. 379]).
Among these [apostles] Peter alone almost everywhere deserved to represent the whole Church. Because of that representation of the Church, which only he bore, he deserved to hear "I will give to you the keys of the kingdom of heaven" (Sermons 295:2 [A.D. 411]).
[I just Googled "Early Fathers on the Primacy of Peter"]