Gelimer, in the meantime, upon learning of the Romans' arrival, immediately notified his brother Ammatas in Carthage to assemble the Vandal forces in the vicinity, as well as to execute Hilderic and his relatives, while his secretary Bonifatius was ordered to load the royal treasure on a ship and sail for Spain if the Romans won. Deprived of his best troops, which were with Tzazon, Gelimer contented himself with shadowing the northward march of the Roman army, all the while preparing a decisive engagement before Carthage, at a place called Ad Decimum ("at the tenth ") where he had ordered Ammatas to bring his forces. The Romans advanced through Thapsus, Leptis Parva and Hadrumetum to Grasse, where for the first time they engaged in a skirmish with the scouts of Gelimer's army. After exchanging blows, both parties retired to their camps. From Grasse, Belisarius turned his army westwards, cutting across the neck of the Cape Bon peninsula. This was the most dangerous part of the route to Carthage, with the fleet out of sight.