Seeking to establish himself as an independent ruler in Africa or even become Roman Emperor, Bonifacius had defeated several Roman attempts to subdue him, until he was mastered by the newly appointed Gothic count of Africa, Sigisvult, who captured both Hippo Regius and Carthage. It is possible that Bonifacius had sought Genseric as an ally against Sigisvult, promising him a part of Africa in return. Advancing eastwards along the coast, the Vandals were confronted on the Numidian border in May–June 430 by Bonifacius. Negotiations broke down, and Bonifacius was soundly defeated. Bonifacius subsequently barricaded himself inside Hippo Regius with the Vandals besieging the city. Inside, Saint Augustine and his priests prayed for relief from the invaders, knowing full well that the fall of the city would spell conversion or death for many Roman Christians. On 28 August 430, three months into the siege, St. Augustine (who was 75 years old) died, perhaps from starvation or stress, as the wheat fields outside the city lay dormant and unharvested. The death of Augustine shocked the Regent of the Western Roman Empire, Galla Placidia, who feared the consequences if her realm lost its most important source of grain. She raised a new army in Italy and convinced her nephew in Constantinople, the Eastern Roman Emperor Theodosius II, to send an army to North Africa led by Aspar. Around July–August 431, Genseric raised the siege of Hippo Regius, which enabled Bonifacius to retreat from Hippo Regius to Carthage, where he was joined by Aspar's army. During the summer of 432, Genseric soundly defeated the joint forces of both Bonifacius and Aspar, which enabled him to seize Hippo Regius unopposed. Genseric and Aspar subsequently negotiated a peace treaty of some sorts. Upon seizing Hippo Regius, Genseric made it the first capital of the Vandal kingdom. The Romans and the Vandals concluded a treaty in 435 giving the Vandals control of the Mauretania and the western half of Numidia. Genseric chose to break the treaty in 439 when he invaded the province of Africa Proconsularis and seized Carthage on October 19. The city was captured without a fight; the Vandals entered the city while most of the inhabitants were attending the races at the hippodrome. Genseric made it his capital, and styled himself the King of the Vandals and Alans, to denote the inclusion of the Alans of northern Africa into his alliance. His forces also