The eastern Roman Emperor Justinian I, who had supported Hilderic, soon declared war on the Vandals, ostensibly to restore Hilderic but more likely to restore North Africa to the Roman Empire. In June 533, Justinian sent an expeditionary force commanded by Belisarius which finally reached Africa in the beginning of September. Meanwhile in Sardinia which formed part of the Vandal domain, Goddas, a Visigoth, whom Gelimer had sent to collect a tax, began to treat with Justinian as an independent sovereign. Gelimer ignorant or contemptuous of Justinian's plans sent a large army consisting of most of the available army in Africa under his brother Tzazo to crush the rebellion meaning that the landing of Belisarius was entirely unopposed.
On landing Belisarius immediately marched for Carthage finally meeting resistance on the 13th of September when he was confronted by Gelimer at Ad Decimum, 10 miles from Carthage. Although outnumbered 11,000 to 17,000 the battle was evenly fought by the Vandals until Gelimer's brother Ammatas was killed at which time Gelimer lost heart and fled. On 14 September 533, Belisarius entered Carthage and ate the feast prepared for Gelimer's in his palace. Belisarius, however, was too late to save the life of Hilderic, who had been slain by Gelimer's orders as soon as the news came of the landing of the imperial army.
The Vandals however were not beaten and on the return of Tzazo from Sardinia, Gelimer again met Belisarius in battle this time at a place about 20 miles from Carthage, called Ticameron. (December 533). This battle was far more stubbornly contested than that of Ad Decimum, but it ended in the utter rout of the Vandals and the flight of Gelimer. He retreated to a mountain fortress on the border of Numidia called Pappua, where he soon found himself under siege by Byzantine forces under Pharas. According to Procopius, when summoned to surrender, Gelimer instead asked Pharas to send him a loaf of bread, a sponge, and a lyre, to make the Winter months on Mt. Pappua more bearable.
Finally in March 534, realizing he had no chance of regaining his kingdom, Gelimer surrendered to Belisarius and accepted the Romans' offer of vast estates in Galatia where he lived to be an old man. His abdication achieved some degree of anecdotal fame, according to Byzantine chronicles, by crying out the verse from Ecclesiastes, 'Vanity of vanities, all is vanity'.