The murder of Roman Emperor Valentinian III, who had betrothed his daughter to Gaiseric's son Huneric, led the Vandal king to invade Italy.

Gaiseric repulsed two major attempts by both halves of the Roman Empire to reclaim North Africa, inflicting devastating defeats on the forces of Majorian in 460 and Basiliscus in 468.

After his father Godigisel's death in a battle against the Franks during the Crossing of the Rhine, Gaiseric became the second most powerful man among the Vandals, only answering to the newly appointed king, his half-brother Gunderic.

He was a man of deep thought and few words, holding luxury in disdain, furious in his anger, greedy for gain, shrewd in winning over the barbarians and skilled in sowing the seeds of dissension to arouse enmity.

The Vandals had suffered greatly from attacks from the more numerous Visigothic federates, and not long after taking power, Gaiseric decided to leave Hispania to his rivals.

[6] After defending the aforementioned Suebian attack at Mérida, Gaiseric led most of his people—possibly as many as 80,000 persons to Northern Africa in 428/429; some scholars claim that this figure represents an exaggeration and the number was probably closer to 20,000.

[11] Once there, he won many battles over the weak and divided Roman defenders and quickly overran the territory now comprising modern Morocco and northern Algeria.

[18] In a surprise move on 19 October 439, Gaiseric captured Carthage, striking a devastating blow at imperial power, taking advantage of the fact that Aetius remained preoccupied with affairs in Gaul.

"[15] In the wake of Gaiseric's assault on Carthage, North African bishop and historian, Victor of Vita, wrote in his Historia persecutionis Africanae provinciae sub Geiserico et Hunerico regibus Vandalorum (History of the Persecution in the Province of Africa under the Vandal Kings Gaiseric and Huneric) that the Vandal king immediately began to unrelentingly persecute adherents of the true Nicene Christian faith.

"[22] Heather doubts Victor of Vita's claim of a deliberate and prompt campaign by Gaiseric to persecute Nicene Christians and instead, avows it was more likely not until after 442, when the combined attempt by Eastern and Western Rome to retake Carthage failed; only then did the Vandal king put "considered religious policies into operation.

[26] Inheriting an already economically efficient and effective state, the tax revenues from his new lands enabled the Vandal conqueror to construct a large fleet that challenged imperial control over the Mediterranean.

[26] Gaiseric presided over a mixture of Vandals, Alans, Goths and Romans in Africa, relying on an ad-hoc administration under auspices of the imperial government to legitimize his rule.

[32] Responding to the actions of Petronius Maximus, Gaiseric moved a large seaborne force from Carthage to Italy and sacked the city in a more thorough manner than even Alaric's Goths had carried out in 410.

[33] Historian Michael Kulikowski notes that unlike Alaric, who besieged Rome as an itinerant barbarian general in "desperate straits," Gaiseric was the king of a flourishing polity and was therefore able to systematically conduct the sack.

[54] After enjoying just a few short years of peace, Gaiseric died at Carthage in 477, succeeded by his son Huneric, who did not have his father's enviable reputation and Vandal authority began to diminish.