August 24 - 410 - The Sack of Rome
Alaric, the first King of the Visigoths, led an army to the gates of Rome in 410, then was allowed through the gates and sacked the city. This is often recorded as the end of the Western Roman Empire, but this singular moment was less of a paradigm shift than the culmination of a variety of problems. Alaric certainly worked hard enough in leading an army from his home at the mouth of the Danube to Italy, but he also exploited long standing political divides. If Alaric hadn't taken Rome, some other Germanic leader probably would have. Nonetheless, Alaric got there first and gets the credit.