A strong force was left to prevent the garrison from making a sortie, and the whole of the troops were then marched away in detachments to the hills to fell and bring down the timber which would be required for the towers and walls, the bareness of the rock rendering it impossible to construct the approaches as usual with earth.

In the first place, a wall, strengthened by numerous small towers, was erected round the whole circumference of the rock; then the approaches were begun on the western side, where attack was alone possible.
This was done by lines of wooden towers, connected one with another by walls of the same material; movable towers were constructed to be pushed forward against the great tower which formed the chief defence of the wall, and on each side the line of attack was carried onward by portable screens covered with thick hide.

In the meantime the Saguntines were not idle.

Showers of missiles of all descriptions were hurled upon the working parties, great rocks from the machines on the walls crashed through the wooden erections, and frequent and desperate sorties were made, in which the Carthaginians were almost always worsted.

The nature of the ground, overlooked as it was by the lofty towers and walls, and swept by the missiles of the defenders, rendered it impossible for any considerable force to remain close at hand to render assistance to the workers, and the sudden attacks of the Saguntines several times drove them far down the hillside, and enabled the besieged, with axe and fire, to destroy much of the work which had been so labouriously carried out.
In one of these sorties Hannibal, who was continually at the front, overlooking the work, was seriously wounded by a javelin in the thigh.
Until he was cured the siege languished, and was converted into a blockade, for it was his presence and influence alone which encouraged the men to continue their work under such extreme difficulties, involving the death of a large proportion of those engaged.