410 AD
On August 24, 410 AD, the Visigoths under King Alaric breached the walls of Rome and sacked the city for three days. Though the Church buildings were largely spared (Alaric respected the bishops), the psychological shock was enormous. For 800 years, Rome had been considered inviolate. News of the sack sent shockwaves throughout the known world.
Pagans seized the opportunity to blame Christianity for Rome's downfall, claiming that abandoning the traditional gods had brought divine punishment. This provoked St. Augustine to write his masterpiece 'The City of God' (De Civitate Dei), in which he argued that the earthly city was always subject to decay and that the true city of God was spiritual and eternal. The work would become one of the most influential books in Western civilization.
St. Jerome, hearing the news from Bethlehem, wrote: 'The city taken, that is, the city believed to be unbreakable and eternal, has been captured.' The sack marked the beginning of the end for the Western Roman Empire. Key Sources: St. Augustine, City of God I-II; St. Jerome, Letter 127; Orosius, Seven Books of History