Born in Rome around the year 305 AD, Pope Damasus came from a family that were originally from the region of Lusitania. His father became a priest at the Church of Saint Lawrence in Rome and he followed in his footsteps by becoming a deacon in his father's church. Pope Damasus was just a child when Constantine I issued his Edict of Milan and was in his early twenties when Constantine reunited the Empire. He was an archdeacon of the Roman Church in 354 AD when Emperor Constantius II banished Pope Liberius to Berea and initially followed him into the exile.
The death of Pope Liberius in 366 caused a succession in the crisis and placed Damasus right in the middle of it. In the early years of the Church, Bishops were elected by the clergy and laity of the local diocese, a method that worked in small tight nit communities unified by outside persecution. As the Church grew and persecutions ended, Emperors in the 4th century began expecting pope-elects to be presented to the court for their approval. When Pope Liberius died, the deacons and laity supported Liberius' deacon Ursinus while the upper class and those who had supported Felix during Liberius' exile supported Damasus. This heated and intense fight spilled over into violence and bloodshed. Though Damasus was declared Pope at a synod in 378 AD and Ursinus condemned, Ursinus would continue to contest his election even after Pope Damasus' death.
His first years as Pope would nearly as difficult as the elections, as many supporters of Arianism fought against him and constantly accused him of murder and adultery; accusations that would constantly be found to be false. The now Pope Damasus I condemned Apollinarianism (That Jesus had a normal human body but a divine mind instead of a human soul) and Macedonianism (denial of the Godhood of the Holy Ghost; followers were known as Pneumatomachi which means Combators against the Spirit in Greek). Pope Damasus I presided over the Council of Rome in 382 AD that determined the canon of Sacred Scripture. Catholic Priest and Historian William Jurgens writes in his book Faith of the Early Fathers:
"The first part of this decree has long been known as the Decree of Damasus, and concerns the Holy Spirit and the seven-fold gifts. The second part of the decree is more familiarly known as the opening part of the Gelasian Decree, in regard to the canon of Scripture: De libris recipiendis vel non recipiendis. It is now commonly held that the part of the Gelasian Decree dealing with the accepted canon of Scripture is an authentic work of the Council of Rome of 382 A.D. and that Gelasius edited it again at the end of the fifth century, adding to it the catalog of the rejected books, the apocrypha. It is now almost universally accepted that these parts one and two of the Decree of Damasus are authentic parts of the Acts of the Council of Rome of 382 A.D."
After the synod of 382, Pope Damasus asked Saint Jerome to join him as the Pope's confidential secretary after he had taken a prominent role in the councils. Saint Jerome wrote of this time as:
"A great many years ago when I was helping Damasus, bishop of Rome with his ecclesiastical correspondence, and writing his answers to the questions referred to him by the councils of the east and west...."
Pope Damasus encouraged Saint Jerome to revise the Old Latin version of the Bible into a more accurate Latin based on the Greek New Testament and Septuagint, which resulted in the creation of the Vulgate. He also was a close friend of those in the Eastern Church and personally helped Peter II of Alexandria when he sought refuge in Rome from the Arians. Pope Damasus supported the appeals to Emperor Gratian for the removal of the altar of victory from the senate and welcomed the edict "De fide Catholica" in 380 by Theodosius I.
Pope Damasus restored access to the tombs of the great martyrs in the Catacombs of Rome and created tables with verse inscriptions. He rebuilt and repaired portions of his father's church known as San Lorenzo fuori le Mura and in total served as Pope for eighteen years. After his death, he was buried with his mother and sister somewhere between the Via Appia and Via Ardeatina.