and to submit to a siege there on the part of the Boii, till
a second legion sent from Rome under the praetor Lucius Atilius
succeeded in relieving army and town, and in suppressing for the
moment the Gaulish insurrection. This premature rising of the Boii
on the one hand, by delaying the departure of Scipio for Spain,
essentially promoted the plans of Hannibal; on the other hand, but
for its occurrence he would have found the valley of the Po entirely
unoccupied, except the fortresses. But the Roman corps, whose two
severely thinned legions did not number 20,000 soldiers, had enough
to do to keep the Celts in check, and did not think of occupying the
passes of the Alps. The Romans only learned that the passes were
threatened, when in August the consul Publius Scipio returned without
his army from Massilia to Italy, and perhaps even then they gave
little heed to the matter, because, forsooth, the foolhardy attempt
would be frustrated by the Alps alone. Thus at the decisive hour and
on the decisive spot there was not even a Roman outpost. Hannibal had
full time to rest his army, to capture after a three days' siege the
capital of the Taurini which closed its gates against him, and to
induce or terrify into alliance with him all the Ligurian and Celtic
communities in the upper basin of the Po, before Scipio, who had
taken the command in the Po valley, encountered him.

Scipio in the Valley of the Po
Conflict on the Ticino
The Armies at Placentia

Scipio, who, with an army considerably smaller and very weak in
cavalry, had the difficult task of preventing the advance of the
superior force of the enemy and of repressing the movements of
insurrection which everywhere were spreading among the Celts, had
crossed the Po presumably at Placentia, and marched up the river to
meet the enemy, while Hannibal after the capture of Turin marched
downwards to relieve the Insubres and Boii. In the plain between
the Ticino and the Sesia, not far from Vercelli, the Roman cavalry,
which had advanced with the light infantry to make a reconnaissance
in force, encountered the Punic cavalry sent out for the like purpose,
both led by the generals in person. Scipio accepted battle when
offered, notwithstanding the superiority of the enemy; but his light
infantry, which was placed in front of the cavalry, dispersed before
the charge of the heavy cavalry of the enemy, and while the latter
engaged the masses of the Roman horsemen in front,