With his brother Primo di Castello, he left as the leader of the second Genoese expedition to the Holy Land. Afterwards, he led a third mission composed of 26 galleys: in that occasion he was able to storm and break down, on the 15 July 1099, the town walls of the Holy City. Then, in 1101, he managed to conquer Cesarea and Tiro, thanks to special devices he personally invented. He planned two wooden towers, installed upon moving wheels, whose height was more than the town walls themselves. It was thus possible to shoot arrows, spears and stones from the upper part of the tower over the besieged town. At the level of the walls, on the other hand, a door and a drawbridge made it possible for the crusaders to break into the higher part of the town. Two very long scythes were installed along the sides, while the outside was entirely wrapped by recently dressed hide, extremely useful to resist crashes and to keep back the fire, as they were soaked in vinegar and other substances.