Gelimer lived from about 480 to 550 A.D. and was the ruler of the Vandal kingdom in North Africa for four years from 530 to 534. The emperor Justinian aspired to restore Roman control over the region, and to this end sent his general Belisarius to expel the barbarian trespassers. This he did. Gelimer was also captured for good measure, and transported back to Byzantium as a prize of war.
It was a Roman custom of the republic and early empire to allow victorious generals, back from their campaigns, to stage a “triumph” in the capital. This was essentially a mixture of parade and public procession where the victor would show the public the prizes of war, exotic animals, captured prisoners, and any other curiosities that might stimulate the fancy of a public hungry for spectacle. Such triumphs had passed out of fashion with the advent of a strong, centralized imperial authority. Emperors were not overly enthusiastic about seeing their generals lauded for things they themselves wanted credit for.
So for whatever reason, Justinian decided to break with precedent and award Belisarius a triumph. According to the historian Procopius (Wars IV.9), about six hundred years had passed since the last time a triumph had been staged in the capital. It was an unprecedented event. (In point of fact, the last non-imperial triumph, according to historian Anthony Kaldellis, was in 19 B.C. when Lucius Cornelius Balbus was granted one for his crushing of the Garamantes in Africa).
Belisarius did not conduct the triumph in the traditional manner. Rather than ride in a carriage, he went on foot from his own house to the hippodrome; once inside he proceeded to approach the imperial reviewing stand to salute the emperor. About the spoils on display in the triumph, Procopius tells us:
There was booty, including whatever is set apart by custom for imperial service, thrones of gold and carriages in which it is customary for the emperor’s wife to ride, and much jewelry made of precious stones, golden drinking cups, and all other things that serve for the imperial table. There was also silver weighing many thousands of talents and all the royal treasure that was worth an extremely great sum…Among these were the treasures of the Jews, which Titus, the son of Vespasian, together with certain others, had brought to Rome after the capture of Jerusalem.
Procopius tells us that when these treasures were put on display, a prominent Jew who had access to some imperial officials protested that the antiquities should be housed in Byzantium; their rightful place, he insisted, was in some appropriate facility in Jerusalem, the place from where they had been taken. Justinian was an extremely religious man–even by the standards of the day–and began to be concerned that the presence of the ancient Hebrew relics under his roof might subject him to some sort of divine curse. So he sent the treasures to Jerusalem under the care of some Christian legates.
Slaves were also paraded in the triumph. Gelimer himself, the deposed and defeated king, was among them; in those days, the defeated were made to taste the full bitterness of their condition by passing symbolically under the yoke (sub iugum). Gelimer and his retinue of slaves were brought into the hippodrome and made to circle the giant stadium before the roaring crowd. We may only speculate as to what thoughts were passing through his mind.
Did he reflect on the transitory nature of earthly power and riches? Did he ruminate on the fickleness of Fortune, that had raised him up from nothing to be king of all the Vandals and Alans, only to hurl him back down to his presently abject condition? Did he take solace, perhaps, in the knowledge that those who cheered his downfall today might see themselves so judged by Fortune tomorrow?
We do not know. What we do know is that as he grimly circled the hippodrome, he paused before the box of the emperor and empress, high upon the reviewing stand. Justinian sat on an elevated seat with officials and spectators on either side.
“He neither wept nor cried out,” says Procopius, “but repeated again and again these words from Biblical scripture, ‘vanity of vanities, all is vanity.'”
Most of the things we are convinced are so important will, in time, recede into the mists of irrelevance. Those who spend their lives, and their efforts, preoccupied with the minutiae of triviality will wake up one day to find themselves old and tired. And that which they once thought was so vital, is now revealed to be a cruel mirage.
 Trans. by Anthony Kaldellis, from Wars IV.9.
 This is also a quote from Ecclesiastes 1.1-2.
Read more about this and related topics in Pantheon.