Scipio moved back to a close blockade of the city, and built a mole which cut off supply from the sea. In the spring of 146BC the Roman army managed to secure a foothold on the fortifications near the harbour. When the main assault began it quickly captured the city's main square, where the legions camped overnight. The next morning the Romans systematically worked their way through the residential part of the city, killing everyone they encountered and firing the buildings behind them. At times the Romans progressed from rooftop to rooftop, to prevent missiles being hurled down on them. It took six days to clear the city of resistance, and on the last day Scipio agreed to accept prisoners. The last holdouts, including Roman deserters in Carthaginian service, fought on from the Temple of Eshmoun and burnt it down around themselves when all hope was gone. There were 50,000 Carthaginian prisoners, a small proportion of the pre-war population, who were sold into slavery. There is a tradition that Roman forces then sowed the city with salt, but this has been shown to have been a 19th-century invention.