Innocent I is known as one of the most energetic popes of the early Church. You will see why, shortly.
Apparently, Innocent was the son of Pope Anastasius, who preceeded him. It is said that he was born March 11, 378, possibly in Albano Laziale, a commune in the province of Rome. If that is the case, Innocent would have been 21 when his father ascended the chair of Peter. To be that popular, Anastasius must have been quite entrenched with the rest of the clergy in Rome and been involved for some years. Thus, Innocent, a motherless child, would have been involved, himself, from an early age. He knew no other life than the Roman clergy. But he knew it well.
At the age of 23, Innocent's father, spiritual as well as physical, died. Innocent was probably a deacon by this time and he was deemed the best choice for new pope, being elected unanimously by the clergy and residents of Rome.
A young man, Innocent had much energy and many interests. The first and foremost was to maintain and extend the authority of the Roman apostolic See. He worked hard to have the papacy seen as the ultimate resort for the settlement of all ecclesiastical disputes. Throughout his reign, he had many opportunities to show this authority.
In 403, John Chrysostum, the archbishop of Constantinople, had defended Origen, the questionable teacher of Alexandria. The current archbishop of Alexandria, Theophilus, deposed John after a synod. Both turned to Innocent, who did not uphold the synod's decision, did not support the deposition and did not support John's successors, until after John's death in 407. He tried to give John back his good name, but that did not happen until the death of Theophilus in 412.
By 404, Innocent had written to bishops in various parts of the empire decreeing that important matters should be sent from episcopal tribunals to Rome, for example, ordinations, questions of celebacy, receptions of converted heretics. He claimed that the discipline of Rome would be the discipline of all. In this vein, he moved against the Montanists, those who thought that their elect few got messages from God, directly. He obtained from the emperor a decree against the Montanist heresy, causing some to reconcile. The emperor did not want heresy; he wanted one religion.
In 405, Innocent became the last word on the canon of the Bible, when he sent the final list to Exsuperius of Toulouse. His list is the same as the list of the Council of Trent, except Paul's letter to the Hebrews.
In 408, the Visigoth, Alaric, who was not nominated supreme military commander by the Emperor Honorius, took out his aggressions on the city of Rome. Laying siege to the town, he terrified the residents. A truce was negotiated so that an embassy of men, including Innocent, could go up to Ravenna, where the emperor was staying. Alaric had offered to stop the siege if his demands were met. The embassy failed to convince the emperor to meet those demands. So the Visigoths began their siege again, preventing the members of the embassy from returning. Rome was conquered and sacked, leaving a few of the churches intact. It was a short occupation and Alaric died soon after. However, the Visigoths returned the next year and repeated their plunder. It is said that these nonbelievers were so impressed by the patience of the Christians, who lost so much, that many chose to be baptized themselves.
Innocent returned to his city in 412. The psychological impact of the years of siege had left the citizens with a negativity towards the future. All Innocent could do was to double down on fixing his Church. In a letter dated June 17 of that year, the pope entrusted supreme administration of the dioceses of Eastern Illyria (now, the Balkan States) to the archbishop of Thessalonica (now Macedonia), as representative of the Holy See, thus becoming vicars of the popes.
Innocent's fight with heresy was not over. In the two years before his death, he was obligated to fight Pelagianism, which taught that human nature was essentially good. The believers denied original sin, denied the necessity of infant Baptism and felt that humans could do good on their own. Thus, Christ's death on the cross was a moral example only. St. Augustine argued that humans are totally dependent on the grace of God for their ultimate end. Councils in 416 and 418, after Innocent's death finally excommunicated the leaders of the Pelagian heresy.
In all his fighting, Innocent had the time and energy to build a beautiful church dedicated to Saints Gervasius and Protasius. It is still standing, after all these years, but has been renamed San Vitale.
As you can see, Innocent fought hard to save and defend the Church doctrine. As he did, the Roman government became more and more pacifist. As a result, the empire died, while the Church rose to new heights.
Pope Saint Innocent, pray for us and give us the energy to hold on, despite the examples handed on to us from those who are our superiors!