Hannibal

We can start with a story from Hannibal's childhood. As mentioned before, the Carthaginians used sacrifice (of both humans and animals) to try and steer the policies of the Gods their way. When Hamilcar decided to go to Iberia (Spain, today) and extend Carthage's empire in that direction, his eldest (nine-year-old) son Hannibal wanted to go along – every boy likes take-your-kid-to-war day. His father agreed and brought Hannibal to the ceremony were he made his sacrifices for good fortune in the upcoming endeavor.

He [Hamilcar] brought Hannibal to the altar and there made him touch the sacred objects and swear to make himself an enemy of the Roman people at the earliest possible opportunity.
Livy, Book XXI, 1

Polybius makes it clear that the "sacred objects" were the sacrificial victims, likely human. This would, I think, impress the oath into the mind of a nine year old boy. Dr Hunt calls it the most "formative" moment in Hannibal's life.

Livy does paint us a picture of Hannibal, but it's not clear what his sources were. We should probably take Livy's "enormous vices" with a grain of salt here. Even so many years later when Livy wrote this, Hannibal remained a hated and feared enemy of Rome. Even Livy's own account holds instances where Hannibal behaved with chivalry and honor.

Hannibal was possessed of enormous daring in facing dangers, and enormous resourcefulness when in the midst of those dangers. He could be physically exhausted or mentally cowed by no hardship. He had the ability to withstand heat and cold alike; his eating and drinking depended on the requirements of nature, not pleasure. His times for being awake and asleep were not determined by day or night. Only the time which he had left from discharging his duties was given to sleep, and it was not brought on by a soft bed or silence – many often observed him lying on the ground, wrapped in a soldier's cloak. His dress was no better than that of his comrades, but his weapons and horses marked him out. On horse or foot he was by far the best soldier; the first to enter battle, he was the last to leave once battle was joined.

The man's great virtues were matched by his enormous vices: pitiless cruelty, a treachery worse than Punic, no regard for truth, and no integrity, no fear of the gods or respect for an oath, and no scruples.

Livy, Book XXI, 4

Polybius shows us that Hannibal never let his own hardships slow his army down in the slightest.

Hannibal himself on the sole remaining elephant got across with much difficulty and suffering, being in great pain from a severe attack of ophthamalia, which finally led to the loss of one eye as he had no time to stop and apply any treatment to it, the circumstances rendering that impossible.
Polybius, Book III, 79

Most of Hannibal's victories came from superior strategy and tactics. In the Battle of Trebia Hannibal used the weather (freezing), a stash of 2,000 of his top troops behind the enemy's rear and a keen understanding of his opponent's hot-headed temper to pull off his first major victory in Italy. At the encirclement maneuver he used at Cannae is a classic that he employed in a novel way, drawing the enemy into a seemingly weak center only to have the wings wrap around him. All of these are still studied at war colleges today as classic examples of their kind.

In addition to being a master of strategy and tactics, Hannibal was a consummate leader of men. Of his early days, Livy says, "one would have found it hard to tell whether he was better liked by the commander or by the army" (Livy Book XXI, 3) and his reputation would only grow from there. No ordinary man could have held together a large multi-national, multi-lingual force for a decade and a half under regular enemy assault. The Romans could go home during the winter, Hannibal and his men had to camp out (although they sometimes captured towns or forts). His forces included Carthaginians, Iberian Celts, slingers from the Balearic Islands, Gauls, and Numidian calvary. Keeping peace among this diversity of soldiers, each with his own language, religion and level of civilization, must have required almost superhuman efforts.

Hannibal was certainly capable of cruelty when necessary. When it was time to kill some prisoners for some reason, he was fond of having them trampled to death by the elephants. When the Taurini tribe refused to join him and holed up in their city (now, the city of Turin in Italy), Hannibal stormed the city and killed every inhabitant as a lesson to the others in the area that his was the side to be on.

…he at first made overtures for their friendship and alliance, but on their rejecting these he encamped round their chief city and reduced it in three days. By massacring those who had been opposed to him, he struck such terror into the neighboring tribes of barbarians that they all came in at once and submitted to him.
Polybius, Book III, 60

So, not exactly a nice man. On the other hand, whenever a high-ranking Roman leader's body was found on the battlefield, it was always buried with full honors according to Roman custom (a favor the Romans never returned, they rolled his brother Hasdrubal's head into Hannibal's camp to try and frighten him, not that it worked). We can also assume that the respect his troops had for him must have been based on trust, so he must have kept his word when dealing with his own troops. He was a complicated man and it's a shame that we know so little about him.

Rome

Polybius, as a historian, tended to focus on the people and events of the war. He gives us little detail about the Roman society of the time. Livy, however, wasn't so restricted. One of the most odd things one reads about the Romans of the time was their religious fervor. In his lectures, Dr Hunt makes the point that the Carthaginians didn't feel that the Romans paid proper attention to their religion and looked down on them as a result. Livy, however, makes it clear that while they may not have been very observant on the battlefield, back home in the cities and shrines they were quite religious – to a point that seems a little crazy today. It's tempting to call their worship of their pantheon "superstition" and let it go, but you have to remember that they believed in their religion just as much as any modern day fundamentalist.

The Romans worried a great deal about portents. If lightning struck a religious structure, or some stones rained down from the sky or the rivers ran with blood, that was a sign the Gods were angry and that they must be carefully assuaged. Livy reports this with so much attention that, under the definition for "prodigy" in the dictionary, I found this:

prodigy: an amazing or unusual thing, esp. one out of the ordinary course of nature : omens and prodigies abound in Livy's work.

So, I guess I'm not the only one who noticed. Livy seems to go out of his way to describe the portents and the formulas used to assuage the various Gods (usually, each portent could be assigned by the priests to an individual God).

Fears were heightened by prodigies that were simultaneously reported from several places. In Sicily, the spears of a number of soldiers had burst into flames, and this had also happened in Sardinia to a staff that a horseman had been holding in his hand while he was doing the rounds of the sentries on the wall. In Sardinia, too, beaches had been lit of with numerous fires, two shields had oozed blood, a number of soldiers had been struck by lightning, and the sun's orb appeared to have grown smaller. At Praeneste, burning stones had fallen from the sky. At Arpi, shields had been seen in the sky and the sun seemed to be fighting with the moon. At Capena, tow moons had arisen during the daytime. The waters at Caere had flowed mixed with blood, and the spring of Hercules itself had streaks of blood in its flow. In the region of ANtium, harvesters found that bloody ears of wheat had fallen into their baskets. At Falerii, a huge fissure seemed to appear in the sky and a blinding light shone out from the opening. The oracular lots had simultaneously shrunk in size, and one of them fell out bearing the words 'Mars is brandishing his spear'. During this same period, in Rome, sweat appeared on the statue of Mars on the Appian Way, and on the figures of the wolves. At Capua, the sky appeared to be on fire, and the moon seemed to fall during a rain shower. Then less spectacular prodigies also won belief – some people's goats growing wool, and a hen turning into a cock and vice versa.
Livy, Book XXII, 1

There had been reports of showers of stones falling on the Aventine in Rome and also, at about the same time, at Aricia. It was reported, too, that blood had flowed profusely from statues amongst the Sabines, and also amid the waters at Caere; and this caused greater alarm because it had occurred quite frequently. In addition, a number of people had been fatally struck by lightning on the vaulted street that used to lead to the Campus Matius.
Livy, Book XXII, 36

As a response to these sorts of terrible signs and portents, the Romans would consult the decimviri sacris faciundis (later a Sibylline Books, which were a record of oracular utterances (follow the link, the story of the books and their origins is interesting). This group would, after consulting the books, determine the correct rites of expiation needed to counter the portents (i.e., make the Gods happy again).

Following the decemvirs, the Senate decided that, in the first instance, a gift of a fifty-pound thunderbolt of gold be made to Jupiter, and gifts of silver to Juno and Minerva. Sacrifices of full-grown victims were to be made to Queen Juno on the Aventine and to Juno at Sospita at Lanuvium. In addition, the married women were to gather together as much money as each could afford and bear it as a gift to Queen Juno on the Aventine, where a lectisternium was also to be held.
Livy, Book XXII, 1

For the same purpose Great Games were included in a vow, and the cost of them was to be 333,333 1/3 asses. In addition, 300 oxen were to be sacrificed to Jupiter, and white oxen, and other sacrificial animals, to numerous other gods. When the vows had been duly formulated, a period of public prayer was proclaimed, and these were attended not only by the urban populace with their wives and children, but also by such country people as had some property, and consequently took some thought for the public good. Then a three-day lectisternium was held under the supervision of the decemvirs for sacrifices.
Livy, Book XXII, 10

Meanwhile, a number of outlandish sacrifices were conducted on instructions from the Books of Fate. These included a Gallic man and woman, and a Greek man and woman, being interred alive in the Forum Boarium, in a spot enclosed with stones which had already been the scene of this very un-Roman practice of human sacrifice.
Livy, Book XXII, 57

It's tempting to laugh at all of this, but the Romans don't seem to have had a sense of humor where religion was concerned. Some of the portents were likely made up on the spot to get out of work or duty: "Gaius, there is blood on my wheat! We must immediately stop this hot and arduous work and pray to the Gods!" Others were perfectly natural, such as the condensation on stone or metal statue that would naturally form on a warm humid morning after a cold night. Others were probably just the delusion of the crowd, not unlike flying saucer scares of today ("Marcus, does the sun seem to be getting smaller to you?"). Yes, modern peoples are susceptible to this sort of thing: only a few weeks ago as I write this, the entire US media dropped everything to follow a balloon that supposedly held a young boy – even when the most cursory observation would show that the balloon was nowhere near large enough to lift a forty-pound kid (how would a ballon capable of lifting forty pounds just drift down to earth a few miles after liftoff?).

The Romans were also unbelievably resolute. Even after losing hundreds of ships, the leading men of Rome donated their own money to build another fleet. Despite losing a significant portion of their males of fighting age, the Romans stuck to their swords and raised another army to fight Hannibal. After Cannae, being short of free men, Rome bought 8,000 "sturdy young men" from the slave population and swore them into service. When Hannibal offered to sell his captives back to Rome for a ransom, the Roman Senate denied the offer, having decided that the captured soldiers hadn't properly done their duty by fighting to the death. Hannibal was forced to put several thousand men to the sword because Rome was too stubborn to take them back.

There is surely no other nation that would not have been crushed by such an overwhelming disaster. One might think of comparing the defeat of the Carthaginians in the sea battle off the Aegates Islands, which crushed their resolve, and made them abandon Sicily and Sardinia and accept tax-paying and tributary status. Or perhaps one might think of the defeat in Africa later sustained by Hannibal himself. These disasters can in no respect be compared with Cannae – except to say that they were borne with less strength of character that the Romans bore theirs.
Livy, Book XXII, 54

Roman strength wasn't limited to character, either. All of their allies, up and down the boot of Italy, were more loyal to Rome than they ever were to Hannibal. Some of them threw in with Hannibal, usually when he was standing at their gates with an overwhelming army, but they were never really loyal to them because it was clear they were only a means to an end for him and not a real ally. Rome was a good friend who ruled benevolently and all of its allies knew this.

(Caution, this last bit is my own opinion) Hannibal lost the Second Punic War because of Roman strength of character (as Carthage lost the First Punic war when Rome's character led to their incredible resolution to become a sea power). Hannibal didn't enter Italy with the siege engines he would need to breech the walls of Rome as he did Sargentum. I don't think he expected to have to besiege Rome, his army was never half big enough for that. Instead, he planned to slice away all of Rome's allies up and down Italy and terrorize Rome into suing for peace. It just didn't work, their character was too strong for him (it was a pretty close thing, however, especially right after Cannae).

It's very tempting to bring in an analogy here with the United States and al Qaeda. After all, the 9/11 attacks were not designed to actually conquer the US, just to scare us into some form of concessions. Osama bin Laden fully expected the US to be bamboozled by the attack. The last thing he expected is that the US would show some backbone and stand up for itself. Hannibal seems to have had the same idea about Rome. I'm not enough of a scholar on this to really support such a speculation, however, so I'll just let this aside be my last word on the subject.

I'm not convinced, either, that Hannibal cared so much to conquer Rome. He had been sworn by his father to hate Romans, not to rule them. As long as he was in Italy, a steady number of Romans died at his hands. He thus kept his faith with his father and his God and that was probably enough for him.

As for Rome, super powers are born by overcoming great adversity (as the US and USSR were born of World War II). Hannibal trained Rome in warfare, they adopted many of his means and tactics. More importantly, Hannibal taught Rome the lesson of professional armies. Up until Hannibal, Rome expected its male citizens to fall in and fight, with only the most cursory training. They got by more on tradition than skill, even the generals weren't necessarily versed in warfare. They had just served their own time in the ranks. Hannibal showed them that professional troops were necessary and Scipio Africanus might be considered their first professional general. Without Hannibal, Rome might never have become the great empire it became.

Note: this entry is part of a series called "Hannibal", which contains the following entries:
     Hannibal Studies
     The Punic Wars
     Hannibal and Rome
     Hannibal in the Alps
     Greatest General of All Time?