Just to back up my previous posts, these are just some of the passages in Livy that reveal a number of naval operations and landings of forces from Africa to the various theaters during the war, which clearly prove it simply wasn’t just one fought from land to land from Spain to Italy.
In the meanwhile the news was brought to Carthage that things had gone badly in Spain and that almost all the communities in that country had gone over to Rome. Mago, Hannibal’s brother, was preparing to transport to Italy a force of 12,000 infantry, 1500 cavalry, and 20 elephants, escorted by a fleet of 60 warships. On the receipt of this news, however, some were in favour of Mago, with such a fleet and army as he had, going to Spain instead of Italy, but whilst they were deliberating there was a sudden gleam of hope that Sardinia might be recovered. They were told that "there was only a small Roman army there, the old praetor, A. Cornelius, who knew the province well, was leaving and a fresh one was expected; the Sardinians, too, were tired of their long subjection, and during the last twelve months the government had been harsh and rapacious and had crushed them with a heavy tax and an unfair exaction of corn. Nothing was wanting but a leader to head their revolt. "This report was brought by some secret agents from their leaders, the prime mover in the matter being Hampsicora, the most influential and wealthy man amongst them at that time. Perturbed by the news from Spain, and at the same time elated by the Sardinian report, they sent Mago with his fleet and army to Spain and selected Hasdrubal to conduct the operations in Sardinia, assigning to him a force about as large as the one they had furnished to Mago. (23.32)
The army sent to Sardinia was defeated there (Livy, 23.40) and shortly afterwards, a naval battle took place in which Hasdrubal was defeated by Titus Otacilius Crassus (23.41) as Hasdrubal was returning to Africa.
Very few were influenced by Hanno’s speech. His well-known dislike of the Barcas deprived his words of weight and they were too much preoccupied with the delightful news they had just heard to listen to anything which would make them feel less cause for joy. They fancied that if they were willing to make a slight effort the war would soon be over. A resolution was accordingly passed with great enthusiasm to reinforce Hannibal with 4000 Numidians, 40 elephants, and 500 talents of silver. (23.13)
But they did not remain quiet long, for just after this battle an order was received from Carthage for Hasdrubal to lead his army as soon as he could into Italy. This became generally known throughout Spain and the result was that there was a universal feeling in favour of Rome. Hasdrubal at once sent a despatch to Carthage pointing out what mischief the mere rumour of his departure had caused, and also that if he did really leave Spain it would pass into the hands of the Romans before he crossed the Ebro. He went on to say that not only had he neither a force nor a general to leave in his place, but the Roman generals were men whom he found it difficult to oppose even when his strength was equal to theirs. If, therefore, they were at all anxious to retain Spain they should send a man with a powerful army to succeed him, and even though all went well with his successor he would not find it an easy province to govern. (23.27) (this passage is relevant to understand the one below)
Although this despatch made a great impression on the senate, they decided that as Italy demanded their first and closest attention, the arrangements about Hannibal and his forces must not be altered. Himilco was sent with a large and well-appointed army and an augmented fleet to hold and defend Spain by sea and land. As soon as he had brought his military and naval forces across he formed an entrenched camp, hauled his ships up on the beach and surrounded them with a rampart. After providing for the safety of his force he started with a picked body of cavalry, and marching as rapidly as possible, and being equally on the alert whether passing through doubtful or through hostile tribes, succeeded in reaching Hasdrubal. After laying before him the resolutions and instructions of the senate and being in his turn shown in what way the war was to be managed in Spain, he returned to his camp. (23.28)
Himilco, who had been for a considerable time cruising with his fleet off the promontory of Pachynus, returned to Carthage as soon as he heard that Syracuse had been seized by Hippocrates. Supported by the envoys from Hippocrates and by a despatch from Hannibal in which he said that the time had arrived for winning back Sicily in the most glorious way, and by the weight of his own personal presence, he had no difficulty in persuading the government to send to Sicily as large a force as they could of both infantry and cavalry. Sailing back to the island he landed at Heraclea an army of 20,000 infantry, 3000 cavalry, and twelve elephants, a very much stronger force than he had with him at Pachynus (24.35)
After Marcellus’ departure from Sicily a Carthaginian fleet landed a force of 8000 infantry and 3000 Numidian horse. (26.21)
In regards to strengthening Hannibal’s brother Mago’s position in northern Italy:
To Mago they sent not only instructions but also 25 warships, a force of 6000 infantry, 800 cavalry and 7 elephants. A large amount of money was also forwarded to him to enable him to raise a body of mercenaries, with which he might be able to move nearer Rome and form a junction with Hannibal. Such were the preparations and plans of Carthage. (29.4)
I honestly believe some of these forces, particularly the one sent to Sardinia, should have actually been sent to Hannibal, he certainly could have done with them!