Johannes Zonaras was a 12th century historian who constitutes a major source for the first 20 books of Dio Cassius: he wrote summaries of that portion of Dio's text which is now surviving only in fragmentary form.

Zonaras 8, 8-9 (transl. Ernest Cary)

8. At this time the Romans began their struggles oversea ; previously they had had no experience at all in naval matters. They now became seamen and crossed over to the islands and to other divisions of the mainland. The first people with whom they warred were the Carthaginians. These were no whit inferior to them in wealth or in the excellence of their land; they were trained in naval science to a high degree of efficiency, were equipped with cavalry forces, infantry, and elephants, ruled the Africans, and held possession both of Sardinia, and the greater part of Sicily; as a result they had con-ceived hopes of subjugating Italy. Various factors contributed to increase their self-confidence, but they were especially proud by reason of their position of independence, since they elected their king under the title of a yearly office and not for permanent rule; and feeling that their efforts were expended in their own behalf, they were brimful of enthusiasm.

The reasons alleged for the war were-on the side of the Romans, that the Carthaginians had assisted the Tarentines, on the side of the Carthaginians, that the Romans had made a treaty of friendship with Hiero. The truth was, however, that they were viewing each other with jealousy and thought that the only salvation for their own possessions lay in the possibility of obtaining also those of the others. While they were thus disposed, a certain incident. broke the truce and provoked them to war. It was of the following nature.

The Mamertines, who had once conducted a colony from Campania to Messana, were now being besieged by Hiero, and they called upon the Romans as a nation of kindred blood. The latter readily voted to aid them, knowing that in case the Mamertines should not secure an alliance with them, they would have recourse to the Carthaginians; and then the Carthaginians would master all Sicily, and from there cross over into Italy. For this island is such a short distance away from the mainland that the story goes that it was itself once a part of the mainland. So the island, thus lying off Italy, seemed to invite the Carthaginians to lay claim also to the land over opposite, could they but occupy Sicily first; and the possession of Messana assured to its masters the control of the strait also.

Though the Romans voted to assist the Mamertines, they did not promptly come to their aid becauseof various hindrances that occurred. Hence the Mamertines, under the spur of necessity, called upon the Carthaginians. These effected peace with Hiero both for themselves and for those who had invoked their aid, so as to prevent the Romans from crossing into the island; and under the leadership of Hanno they kept guard over the strait and the city. Meantime Gaius Claudius, a military tribune, sent ahead with a few ships by Appius Claudius, had arrived at Rhegium. But to sail across was more than he dared, for he saw that the Carthaginian fleet was far larger. So he embarked in a skiff and landed at Messana, where he talked to the Mamertines as long as the time permitted. When the Carthaginians spoke in opposition, he returned without accomplishing anything at the time; but later, ascertaining that the Mamertines were at odds - they did not wish to submit to the Romans, and yet were weary of the Carthaginians - he sailed over again. Among other remarks which lie made to tempt them he declared that the object of his presence was to free the city, and that as soon as their affairs could be set in order, he would sail away. He also commanded the Carthaginians either to withdraw, or, if they had any just plea, to offer it.

Now when not one of the Mamertines, by reason of fear, opened his lips, and the Carthaginians, who were occupying the city by force, paid no need to him, he said: " The silence on both sides affords sufficient evidence. On the part of the invaders it shows that they are in the wrong, since they would have justified themselves if their purposes were at all honest ; and on the part of the Mamertines, that they covet freedom, since they would have spoken freely if they had espoused the cause of the Carthaginians." And he promised to aid them. At this a tumult of applause arose from the Mamertines. He then sailed back to Rhegium, and a little later forced a pas-sage across with his entire fleet. However, partly because of the numbers and skill of the Carthaginians, but chiefly owing to the violence of the current and to a storm that suddenly came up, he lost some of his triremes and barely succeeded in getting back safely to Rhegium with the remainder.

9. However, the Romans did not avoid the sea be-cause of their defeat. Claudius proceeded to repair his ships, while Hanno, wishing to throw the respon-sibility for breaking the truce upon the Romans, sent to Claudius the captured triremes and was restoring the captives; and he urged him to agree to peace. When the other would listen to nothing, he threatened that he would never permit the Romans even to wash their hands in the sea. But Claudius, now that he had become acquainted with the strait, watched for a time when the current and the wind both bore from Italy toward Sicily, and then sailed to the island, encountering no opposition. So, discovering the Mamertines at the harbour, he convened an assembly and talked to them, finally persuading them to send for Hanno; for the latter had already become suspicious of their movements and had established himself on the citadel, which he was guarding. Now Hanno was unwilling to come down, but fearing that the Mamertines might allege injustice on his part and revolt, he finally entered the assembly. After many words had been spoken to no purpose by both sides, one of the Romans seized him and, with the approval of the Mamertines, threw him into prison.

Thus, under compulsion, Hanno left Messana entirely. The Carthaginians punished him, and sent a herald to the Romans bidding them leave Messana and depart from all of Sicily by a given day; they also set an army in motion. And when the Romans paid no heed, they put to death the mercenaries serving with them who were from Italy, and made an assault upon Messana, accompanied by Hiero. They besieged the city and kept guard over the strait, to prevent any troops or provisions from being conveyed to the foe. The consul learned of this when he was already close at hand; and finding numerous Carthaginians disposed at various points about the harbour under pretence of carrying on trade, he resorted to deception in order to get safely across the strait, and thus succeeded in anchoring off Sicily by night. His place of landing was not far from the camp of Hiero, and he joined battle without delay, thinking that his sudden appearance would be most likely to inspire the enemy with fear. When they came out to withstand the attack, the Roman cavalry was worsted but the heavy-armed infantry prevailed. Hiero retired temporarily to the mountains and later to Syracuse.

When Hiero had retired, the Mamertines recovered courage because of the presence of Claudius. Claudius therefore assailed the Carthaginians, who were now isolated, and attacked their rampart, which was situated on a kind of peninsula. É In an attempt to carry this point by force the Romans fared badly and withdrew under a shower of missiles. The Africans then took courage and sallied out, pursuing the fugitives, as they thought them, beyond the narrow strip of land. Thereupon the Romans wheeled about, routed them, and killed many, so that they did not issue from the camp again, at least so long as Claudius was in Messana.