St. Leo I (ca. 400-461) was pope from 440 to 461. He strengthened the papal office and thus earned the title of father of the papacy. He played a large role in the disputes over the nature of Christ, and his views were accepted by the Council of Chalcedon.

The 5th century saw the rapid deterioration of Western civilization. At the beginning of the century the Goths entered northern Italy and in 410 under Alaric entered and sacked Rome. The Roman Empire in the following years changed from unified dominion to a divided and often warring group of local states. The growth of the Christian Church was the precise opposite of the decline of the empire. In the preceding 4 centuries the Church had not only spread over the civilized world but had also developed organizational patterns similar to those of the empire. Local cities were governed by bishops, of whom the...