Obliged to hurry into Spain, he left some of his best troops under his lieutenants C. Trebonius and D. Brutus to continue operations against Marseilles; the former was in command of the land forces, and Brutus was admiral of the improvised fleet. The people of Marseilles were now reinforced by Domitius, one of Pompey’s most trusted generals, and they managed to scrape together a fleet of seventeen galleys. This fleet received orders to attack that of Brutus, and it shot out of the harbour. Brutus awaited it, drawn up in crescent form. His ships were cumbrous, and not manned by such dextrous navigators as the Greeks. But he had furnished himself with grappling irons, and when the Greek vessels came on, he flung out his harpoons, caught them, and brought the enemy to the side of his vessels, so that the fight became one of hand to hand as on platforms, and the advantage of the nautical skill of the Massiliots was neutralised. They lost nine galleys, and the remnant with difficulty escaped back into port. The besieged, though defeated, were not disheartened. They sent to friendly cities for aid, they seized on merchant vessels and converted them into men of war, and Pompey, who knew the importance of Marseilles, sent Nasidius with sixteen triremes to the aid of the invested town. Again their fleet sallied forth. This time they were more wary, and backed when they saw the harpoons shot forth, so that the grappling irons fell innocuously into the sea. Finding all his efforts to come to close quarters with the enemy unavailing, Brutus signalled to his vessels to draw up in hollow square, prows outward. Nasidius, who was in command of the Massiliot fleet, had he used his judgment, should have waited till a rough sea had opened the joints of the opposed ranks, and broken the formation. Instead of doing this, he endeavoured by ramming the sides to break the square, with the result that he damaged his own vessels, which were the lightest and least well protected at the bows, far more than he did the enemy. Seeing that his plan was unsuccessful, he was the first to turn his galley about and fly. Five of the Massiliot vessels were sunk, four were taken, and those that returned to the port were seriously damaged. On land the besieged had been more successful; they had repelled all attempts of Trebonius to storm the place. When he mined, they countermined, or let water into his galleries, and drowned those working in them. When he rolled up his huge wooden towers against the walls, the besieged rushed forth and set them on fire.