Pulcheria was born on 19 January in the year 399 (some place her birth in 398) into the imperial house of Theodosius, which ruled the Eastern Empire from Constantinople. Her father was the emperor Arcadius, a weak prince too easily governed by others, and her mother was the empress Aelia Eudoxia, whose quarrel with the archbishop St. John Chrysostom troubled the Church of the capital. Of the children of that marriage, an elder sister, Flaccilla, died young; Pulcheria was followed by Arcadia, by Theodosius, born in 401, and by Marina. She lost her mother in 404, when she was scarcely five, and her father on 1 May 408, when she was nine, leaving her brother Theodosius II sole emperor at seven years of age under the guardianship of the praetorian prefect Anthemius.
From her infancy, as Butler writes, her prudence and piety made her "the miracle of the world." On 4 July 414 — a date some older accounts give as 14 July — the girl of fifteen was proclaimed Augusta and made partner in the imperial dignity, charged with the care and instruction of a brother only two years younger than herself. Her steadiness and capacity supplied for her want of years. She surrounded Theodosius with the most learned and virtuous masters, taught him deportment, speech, horsemanship, and the bearing befitting an emperor, but made it her first care to instil into him the love of God, devotion in prayer, reverence for the places of divine worship, and zeal for the Catholic Church, knowing well that every other accomplishment is useless, and often dangerous, without religion.
On the day she was raised to the purple she consecrated her virginity to God, taking as witnesses of her resolve God himself, the priests, and all the subjects of the Roman Empire; her sisters Arcadia and Marina followed her example. She admitted no man into her palace, that no cause of scandal or intrigue might arise. Under her the imperial court took on the tone of a monastery: the sisters laid aside the jewels and sumptuous apparel worn by the ladies of the palace, fasted twice a week, chanted the psalms and recited the Scriptures by day and by night, were assiduous in the house of prayer, and, as the historian Sozomen records, showed great charity toward strangers and the poor. The Senate set up her bust among those of the emperors; the historian Philostorgius says that she handled the imperial rescripts during her brother's minority, and Sozomen that she governed the state until he came of age.
Her years as Augusta were not without conflict. War broke out with Sassanid Persia after the Persian king Yazdegerd put to death a Christian bishop, and the soldiers of the empire went out, in the words of the historian Socrates, "ready to do anything for the sake of Christianity." The court and the people attributed the safety of the Roman arms to the vows of the imperial virgins, so that Pulcheria's consecrated chastity was proclaimed as the empire's true defence.
Her charity was famous. She raised churches and hospices for the poor in and around Constantinople, and her building works were so extensive that the eleventh region of the city was called the Pulcherianai after her. She restored bishops who had been unjustly deposed, and brought home the relics of holy men — among them those of St. John Chrysostom, whom her own mother had driven into exile, and later those of the martyred archbishop St. Flavian — receiving them with honour into the churches of the capital: a striking act of reparation and filial piety toward the Church. The famous Trier ivory has been understood as depicting an Augusta, thought by many to be Pulcheria, receiving such relics into the city.
Her brother's marriage in 421 to Athenais, the daughter of an Athenian philosopher, baptized and renamed Eudocia, brought rivalry into the palace; later writers say that the empress and the eunuch chamberlain Chrysaphius turned Theodosius from his sister's counsel, and that Pulcheria withdrew for a time from the palace to the Hebdomon, some seven miles from Constantinople. She bore this eclipse without bitterness, and adversity found her as invincible as prosperity had found her humble.
Her greatest service was to the faith. When Nestorius, archbishop of Constantinople, sought to diminish the title Theotokos, Mother of God, Pulcheria stood against him, though he attacked her by slander and even removed her image and her offering of an altar cloth from the sanctuary. With Eusebius of Dorylaeum and other allies she supported St. Cyril of Alexandria, and at the Council of Ephesus in 431 the title Theotokos was declared orthodox and Nestorius deposed. When in 449 the assembly at Ephesus that Pope St. Leo the Great called the "Robber Council" overturned the truth by violence, and Archbishop Flavian died of the blows he received there, Pulcheria stood with Leo and his Tome, which confessed the two natures of Christ.
On 26 July 450 Theodosius II died of a fall from his horse while hunting. Since he left no son, the legitimacy of the dynasty rested upon his sister. Allying herself with the general Aspar, Pulcheria gave her hand to Marcian, a Roman tribune of modest birth, on the express condition that he honour her vow of virginity, which he faithfully did; the Church declared that Christ himself sponsored so unusual a union. Marcian was raised to the throne in 450, and the corrupt Chrysaphius was put to death. Together the imperial couple summoned the Council of Chalcedon in 451, where four hundred and fifty-two bishops condemned both Nestorius and Eutyches, embraced the doctrine of Cyril and of Leo, and confessed Christ as at all times after the Incarnation fully God and fully man, and Mary as Theotokos. The assembled fathers acclaimed Marcian a new Constantine and Pulcheria a new Helena. Pope Leo, in writing to her, praised her great piety and her hatred of the errors of the heretics.
The last years of her life she devoted to the Mother of God, dedicating in Constantinople three churches to the Blessed Virgin: the Hodegetria, St. Mary of Blachernae, and the Chalkoprateia — sanctuaries that would shape Marian devotion in the East for centuries. She died in 453, most probably in Constantinople, and by her will distributed all that remained of her wealth to the poor. The city mourned her as its own, for she had loved its people and they had loved her. The Church, East and West, honours her as a saint, and the Roman calendar keeps her memory on 10 September.
May St. Pulcheria, virgin and empress, obtain for us the grace to guard purity of heart, to use whatever authority we possess for the poor and for the truth of the faith, and to remain, like her, humble in prosperity and unshaken in trial.