hes the Communications

Thereupon Caesar formed his plan. He ordered portable boats
of a light wooden frame and osier work lined with leather,
after the model of those used in the Channel among the Britons
and subsequently by the Saxons, to be prepared in the camp
and transported in waggons to the point where the bridges had stood.
On these frail barks the other bank was reached and, as it was found
unoccupied, the bridge was re-established without much difficulty;
the road in connection with it was thereupon quickly cleared,
and the eagerly-expected supplies were conveyed to the camp.
Caesar's happy idea thus rescued the army from the immense peril
in which it was placed. Then the cavalry of Caesar which in efficiency
far surpassed that of the enemy began at once to scour the country
on the left bank of the Sicoris; the most considerable
Spanish communities between the Pyrenees and the Ebro--Osca, Tarraco,
Dertosa, and others--nay, even several to the south of the Ebro,
passed over to Caesar's side.

Retreat of the Pompeians from Ilerda

The supplies of the Pompeians were now rendered scarce
through the foraging parties of Caesar and the defection
of the neighbouring communities; they resolved at length to retire
behind the line of the Ebro, and set themselves in all haste to form
a bridge of boats over the Ebro below the mouth of the Sicoris.
Caesar sought to cut off the retreat of his opponents over the Ebro
and to detain them in Ilerda; but so long as the enemy remained
in possession of the bridge at Ilerda and he had control of neither ford
nor bridge there, he could not distribute his army over both banks
of the river and could not invest Ilerda. His soldiers therefore
worked day and night to lower the depth of the river by means of canals
drawing off the water, so that the infantry could wade through it.
But the preparations of the Pompeians to pass the Ebro were sooner
finished than the arrangements of the Caesarians for investing Ilerda;
when the former after finishing the bridge of boats began their march
towards the Ebro along the left bank of the Sicoris, the canals
of the Caesarians seemed to the general not yet far enough advanced
to make the ford available for the infantry; he ordered
only his cavalry to pass the stream and, by clinging to the rear
of the enemy, at least to detain and harass them.

Caesar Follows

But when Caesar's legions saw in the gray morning the enemy's columns
which had b