The Vandals were a Germanic tribe that first appeared in C.E. 166, settling between the Elbe and Vistula, in the east of Germany. Their origins are uncertain and there are widely differing opinions on this subject. It seems the most popular theory is that they originated from Poland, but it is also claimed that they originated from Denmark, Sweden or Norway. Their name is derived from the Latin term Vandilli, the name by which Tacitus referred to the tribe in his book Germania. While their beginnings are nothing to marvel over, they would become the strongest German tribe to challenge Roman imperialism, and would eventually be the final push to tip Rome over the edge.
Early Vandal history is rather mundane. They did not engage in much activity with Rome, posed no threat and were simply one of the free Germanic tribes. This all began to change in c. 370 C.E. as the warlike Huns from Central Asia began to move through Southern Russia. They first conquered and subjugated the Alans, a Russian tribe of Scythian descent. Most fell under Hun rule, but a small portion managed to flee westward into Vandal territory. Disturbed by this migration and fearing they would be next for the Huns to conquer, the Vandals began to stir. The Ostrogoths, whose kingdom was next in line for the Huns to conquer, sent a force to prevent any further Hunnic expansion, but were defeated and forced to flee. When the Huns pushed forward, the Ostrogoths began to migrate westwards too, pushing the Angles, Saxons, Franks and Visigoths into Roman Gaul. Fearing war, Rome sought to appease the tribes it saw as a threat and opened its borders to the Franks and Visigoths. Seeing this migration, and already frightened, the Vandals fled and began pressing towards Gaul.
During this period there were two tribes of Vandals, much like there were two tribes of Goths. While sharing a line of descent, the two Vandal tribes, Asding and Siling, were distinct. The Asding Vandals fled first, provoking another Germanic tribe, the Suebi, to flee with them. When the Huns finally arrived near Vandal territory, the Siling Vandals, fled also, the Alan refugees moving with them. The Huns chased the migrating Vandals, Suebi, and Alans, but ceased when they came into close proximity with the river Rhine, the Huns still fearing war with Rome. The tribes were now pressed between the Huns, on one front, and the Roman guard on the other, which protected Roman lands from unauthorized German migration. They chose to press on regardless, and the might of the four migrating tribes with nothing to lose defeated the thinned defenses the Romans had along the river in C.E. 406. For months the four tribes wandered Gaul as more and more Germans flooded through the gap they had made in the Roman defences. Angered, the Romans hired the Franks to chase the Vandals out of Gaul. After a defeat, they migrated south into Spain. The Siling Vandals and Alans settled in Baetica to the south and the Asding and Suebi settled Galicia to the north. The tribes absorbed the local culture, becoming Arian.
This was not to last, however, as the Romans soon decided that they wanted the Siling Vandals and Alans out of Southern Spain. They hired the Visigoths, and they crushed the united tribes. The Alan Chief was killed, and what remained of the Alans pledged themselves to the Siling Vandal Chief, Gunderic. It seemed the end of the Siling Vandals and Alans; however, Rome realised its mistake in allowing the Visigoths unchallenged dominance of Spain and so offered the Vandals to resettle in south eastern Gaul, with the intention that they would keep the Visigoths in check. The surviving Siling and Alans settled from Galicia to the south eastern coast of Gaul, and the Asding united with their brethren, establishing the Vandal kingdom in C.E. 420 under King Gunderic of the Vandals and Alans; the Suebi remaining independent, but would later be conquered by the Visigoths. After several victories against the Visigoths, the Vandal kingdom was expanded and consolidated. Many ports were captured with many galleys within, and the Vandals now had a powerful fleet and were the first Germanic tribe with a Mediterranean navy.
In C.E. 428 Gunderic died and was succeeded by Gaiseric. He made peace with the Huns, then led the Vandals to war, winning several victories against the Visigoths and Romans in Spain. Yet they were now to abandon their kingdom and migrate yet again. The reasons for this are uncertain, and there seems to be three theories. The first was because the war turned against them and pressure from the Visigoths became too great; the second was because rebellious Roman governor of North Africa, Boniface, invited them there; the third was because King Gaiseric had injured himself, no longer able to ride in battle, and thirsted for the raid, so deigned to do so by sea. Whatever the reason, the same year Gaiseric came to power he migrated from Spain with approxiametely 80,000 men consisting of Vandals, Alans, Romano-Iberians and ex-slaves. He conquered from the eastern coast of North Africa, as far south as Mauritania, to Tingi (modern day Tangiers). While they had been fairly lenient in Spain, King Gaiseric was a staunch Arian and did not tolerate Roman Catholicism. Catholics were tortured and killed, churces looted and destroyed, Catholic art and literature burnt, and hence we see where the modern day meaning of vandal comes from. The Vandals did not, however, senselessly destroy; there was always a point to it, and they could indeed be appeased by riches and land from Rome.
Byzantium sent troops to defeat the Vandals, but were defeated repeatedly. By C.E. 430 the Vandals had expanded across to Hippo Regius, consolidated their kingdom and established a seat of power at Hippo Regius. King Gaiseric made good relations with the Berbers (native, nomadic Africans) and Moors (Mauritanian Africans), recruiting many to his side, and an uneasy peace was made with Byzantium. The Vandals began raiding the Meditteranean, allowing any under their domain (Berber, Moor, Romano, Vandal etc.) to raid Rome by their flag, sending back a portion of the plunder to the Vandals. This raiding was, at times, very destructive, hence perpetuating the misconception that Vandals destroyed senselessly. However, it must be noted that these raiders, while acting under the Vandal flag, were still independent, and were not ordered to destroy by the Vandal crown. In C.E. 434 Byzantium withdrew its army from Carthage and officially recognised the new Vandal kingdom - this was a huge blunder. Carthage was still a major port, and had a large amount of Galleys in it. Seeing this, and noticing it was weakly garrisoned, Gaiseric made a surprise attack in C.E. 439, capturing the city. The Vandals were now the strongest Germanic tribe and posed a huge threat to Rome.
In C.E. 441 Gaiseric moved again, capturing Sicily. Now Gaiseric set his eyes on Rome. He began raiding Corsica, Sardinia and the eastern coast of Italy. By C.E. 455 Rome had been sacked three times, first by the Huns, then the Franks, then the Visigoths. Seeing its weakened state, Gaiseric now stood at the gates of Rome. Terrified, Emperor Maximus fled, but the people noticed him as he tried to slip out and stoned him to death. The Pope, fearing destruction and death in Rome, approached Gaiseric and made a deal with him. The gates of Rome were opened and the Vandals allowed in without resistance so long as there was no pillaging, slavery or killing. Gaiseric agreed and the Vandals loaded their fleet up with the treasures of Rome. Furious at the Vandal occupation of Italy, a Roman general, Majorian, rallied an army and drove them from Italy in C.E. 459. He then built a fleet to defeat the Vandals once and for all but was unsuccesful. The Vandals continued to raid and expand, capturing Corsica and Sardinia in C.E. 461. It was this looting of Rome, and the continuing raids since then, that was the final catalyst to the fall of Rome. The Vandals deprived the Romans of such wealth that in C.E. 476 the Ostrogoths marched into Rome, virtually without resistance, and Theodric the Goth sat upon the Roman throne.
Now the Byzantines began to fear the Vandals, and so deigned to aid Rome once again. Emperor Leo ordered the construction of an immense fleet that drained the coffers of Byzantium and sent the Empire into bankruptcy for years to come. He sent the fleet out under the command of General Basiliscus in C.E. 468, and they were initially succesful in driving the Vandals back and capturing Carthage. Gaiseric retreated to Hippo Regius, then arranged a cease fire with Byzantine - this was yet another mistake. Under the cover of night, Gaiseric broke the cease fire and made a sneak attack on the Byzantine ships in port at Carthage. The fleet was decimated and the Byzantine troops were forced to flee. Carthage was recaptured. In order to prevent Rome or Byzantium from ever gaining such a strong foot hold again, Gaiseric ordered the destruction of all Roman fortifications (again perpetuating the impression of senseless destructiveness). Gaiseric managed to properly consolidate his kingdom and arrange a peace with Rome and Byzantium once more before he died in C.E. 477. After this the Vandal Kingdom only began to dwindle, the Ostrogoths slowly capturing Sicily and reducing Corsica and Sardinia. King Huneric ruled from C.E. 477 - 484, King Gunthamund from C.E. 484 - 496, King Thrasamund from C.E. 496 - 523, and finally, after a period of political unrest, King Gelimer from C.E. 530 - 533. All this quick shifting of Kings was from political intrigue within the kingdom, the King being overthrown several times in quick succession. This weakened the kingdom and, coupled with the fact that none of these Kings had the statesmanship of Gaiseric, turned their subject peoples against them, the Moors putting presure on the kingdom.
After securing peace with the Sassanids (the tribe that had overthrown the Parthians, or Persians), Emperor Justinian, or Justinian the Great, gave the orders to construct a fleet to defeat the Vandals once and for all. In C.E. 533 the Byzantine fleet set sail under the command of General Belisarius and with a force half the size of the Vandals managed to dislodge them from Carthage at the Battle of Ad Decium. The Vandals retreated into Numidia, then after regathering their forces marched back on Carthage, but were defeated yet again at the Battle of Ticameron. King Gelimer attempted to take what was left of the Vandals, along with the Roman treasure, and seek refuge with the Visigoths in Spain, but was intercepted by the Byzantines. He then fled into the mountains and was harboured by a Moor tribe, but was discovered and captured by the Byzantines as they conquered the remainder of the Vandal kingdom in December C.E. 533, marking the end of the Vandals once and for all.
Sources:
http://en.wikipedia.org/wiki/Vandals
http://www.roman-empire.net/articles/article-016.html
http://www.fordham.edu/halsall/ancient/procopius-vandals.html
Tacitus' Germania