 Sardinia and Libya were already conquered by Marcellinus and Heraclius , when Basiliscus cast anchor off the Promontorium Mercurii , now Cap Bon , opposite Sicily , about forty miles from Carthage . Geiseric requested Basiliscus to allow him five days to draw up the conditions of a peace . During the negotiations , Geiseric gathered his ships and suddenly attacked the Roman fleet . The Vandals had filled many vessels with combustible materials . During the night , these fire ships were propelled against the unguarded and unsuspecting Roman fleet . The Roman commanders tried to rescue some ships from destruction , but these manoeuvres were blocked by the attack of other Vandal vessels . 
