Geiseric the Lame (c. 389 – January 25, 477), also spelled as Gaiseric or Genseric, was the King of the Vandals and Alans (428–477) and was one of the key players in the troubles of the Western Roman Empire in the 5th century. During his nearly 50 years of rule, he raised a relatively insignificant Germanic tribe to the status of a major Mediterranean power — which after he died, entered a swift decline and eventual collapse.

Africa
In 455, Roman emperor Valentinian III was murdered on orders of Petronius Maximus, who usurped the throne. Geiseric was of the opinion that these acts voided his 442 peace treaty with Valentinian, and within weeks, on May 31, King Gaiseric and his men landed on Italian soil and marched on Rome, where Pope Leo I implored him not to destroy the ancient city or murder its inhabitants. Geiseric agreed and the gates of Rome were thrown open to him and his men.
Maximus, who fled rather than fight the Vandal warlord, was killed by a Roman mob outside the city. Although history remembers the Vandal sack of Rome as extremely brutal (and their act made the word vandalism a term for any wantonly destructive act), in actuality Geiseric honored his pledge not to make war on the people of Rome, and the Vandals did not wreak great destruction (or even any notable destruction) in the city; they did however take gold, silver and many other things of value away from the city. He also took with him Empress Licinia Eudoxia, Valentinian's widow, and her daughters, including Eudocia, who married Geiseric's son Huneric after arriving in Carthage, and many important people were taken hostage for even more riches.
In 468, Geiseric's kingdom was the target of the last concerted effort by the two halves of the Roman Empire. They wished to subdue the Vandals and end their pirate raids. But the Vandal king, against long odds, defeated the eastern Roman fleet commanded by Basiliscus off Cape Bon. It has been reported that the total invasion force on the fleet counted 100,000 soldiers. The Romans abandoned the campaign and Geiseric remained master of the western Mediterranean until his death, ruling from the Strait of Gibraltar all the way to Tripolitania.
Following up the Byzantine defeat, the Vandals tried to invade the Peloponnese but were driven back by the Maniots at Kenipolis with heavy losses.
In 474, Geiseric made peace with the Eastern Roman Empire. Finally, on January 25, 477, at the advanced age of 87 (some sources say 77), King Geiseric died at Carthage.