At the end of spring - 149, the two consuls nevertheless decide to enter the campaign. They share the task. Manilius will attack the triple enclosure established on the isthmus, while Censorinus is heading with other troops and the fleet towards the coastal strip which separates the lake and the Gulf of Tunis to the south of the ports. The wall is lower and weaker there than elsewhere. But a first, then a second attack are repelled. Moreover, Hasdrubal camped in the rear of the Roman army which he threatened, and the two consuls decided to establish two entrenched camps to protect their troops. Building these machines requires wood, and Censorinus crosses the lake to find it; Phaimas, with the Punic cavalry then falls on the woodcutting soldiers, disperses them and kills a large number of them. Gradually, however, the Romans managed to obtain wood and build two large towers which housed rams. Censorinus had the shoreline filled in and widened by filling in part of the lake. He places one of his machines there, set in motion, says Appian, by 6,000 infantry; the other will be on a rowing boat. If Manilius still fails on the isthmus, Censorinus succeeds, thanks to his towers, in making a breach in the wall; but when night came, the Carthaginians repaired the damage and, making a daring sortie, set fire to the terrible machines.
There is still a breach in the wall which could not be completely sealed and, the next day, the Romans rush into the city despite the advice of the tribune Scipio Emilian who strongly criticizes the recklessness of the consul. Events prove him right; the Carthaginians in arms awaited their enemies whom they drove back with very heavy losses; the engaged corps is narrowly saved by Scipio's soldiers placed to cover an eventual and hasty retreat.
The two consuls then renounce these fruitless attacks and resign themselves to a blockade which will be long and difficult. Hasdrubal and Phaimas hold the countryside and still manage to supply the city. The blockade by sea is not very effective because, when the favorable wind blows, boats launched at full speed manage to enter the port. In addition, the Carthaginians sent on the Roman fleet fireships made of barques with sails spread and filled with flaming wood and tow.
The damage was considerable. In the camp of Censorinus, the miasmas and fetid odors which rise from the lake develop the epidemics. The consul is obliged to set up his camp further from the walls, by the sea. Then he leaves for Rome where he will preside over the elections.