Therefore the statement, that the Roman preponderance at sea had a decisive effect upon the course of the war, needs to be made good by an examination of ascertained facts.

Thus the kind and degree of its influence may be fairly estimated.
[Illustration: MEDITERRANEAN SEA] At the beginning of the war, Mommsen says, Rome controlled the seas.
To whatever cause, or combination of causes, it be attributed, this essentially non-maritime state had in the first Punic War established over its sea-faring rival a naval supremacy, which still lasted.

In the second war there was no naval battle of importance,--a circumstance which in itself, and still more in connection with other well-ascertained facts, indicates a superiority analogous to that which at other epochs has been marked by the same feature.
As Hannibal left no memoirs, the motives are unknown which determined him to the perilous and almost ruinous march through Gaul and across the Alps.

It is certain, however, that his fleet on the coast of Spain was not strong enough to contend with that of Rome.

Had it been, he might still have followed the road he actually did, for reasons that weighed with him; but had he gone by the sea, he would not have lost thirty-three thousand out of the sixty thousand veteran soldiers with whom he started.
While Hannibal was making this dangerous march, the Romans were sending to Spain, under the two elder Scipios, one part of their fleet, carrying a consular army.