Final answer:
The Visigoths were the first group to sack Rome in 410 CE, an event followed later by the Vandals in 455 CE.
Step-by-step explanation:
The first invaders to sack Rome in history were the Visigoths. These Germanic invaders breached the walls of Rome in 410 CE, under the leadership of their king Alaric. This event was a significant shock to the Roman Empire which considered their capital to be impregnable, and it marked the beginning of the end for the Western Roman Empire as various barbarian groups began to encroach on Roman territory. Following the Visigoth sack, the Vandals also attacked and sacked Rome in 455 CE, an event which influenced the use of the word 'vandal' in modern language to mean a malicious destroyer of property.