Under the year 185 BC Livy (39.23.5) mentions the threat of war with Perseus, the son of Philip V of Macedon. He says that the beginnings lay not with Perseus but with his father, who would have waged it if he had lived. Quintus Marcius, sent to Macedon in 183 to investigate the state of affairs there (P.23.8 and 10), reported similarly. At Rome by 172 (L.42.26.2–5) Genthios, son of Pleuratos, of Illyria was under suspicion as a Macedonian sympathiser, and Perseus was known to have sent envoys to ask for the support of Eumenes II, Antiochos IV and Ptolemy V, but all three had remained loyal to their treaties with Rome. Rhodes sent envoys to protest her loyalty in the face of suspicions to the contrary.

The reaction of the Senate (L.42.27 1–8) was to resurrect the fleet which had been laid up in the dockyards since the end of the Syrian war. 50 fives were to be inspected for seaworthiness and the Sicilian squadron was to be repaired and made ready for service if additional ships were needed. In the event 38 fives were launched at Rome and 12 in Sicily. Naval personnel were to be enrolled for the 50 ships, half from the freedmen and half from the allies, and an army of 8000 infantry and 400 cavalry put in readiness. In 171 (L.42.29.1) ‘all the kings and states in Europe and Asia were turning their minds to reflect on the Macedonian and Roman war’. Antiochus IV saw in it an opportunity, while the Roman attention was directed elsewhere, to wage war against the young Ptolemy and his guardians, who in turn were preparing for war against Antiochos to defend their right to Koile-Syria, at that time in Antiochos’s possession. The previous year (P.27.3, L.42.45) Rome had sent an embassy to Asia and among the islands to encourage her allies to join her in a war against Macedon. Rhodes was particularly important because it could provide material help, her president Hagesilochos ‘having advised the Rhodians to commission ( literally to fit hypozomata to: p. 356) 40 ships’, so that they could act instantly as the occasion arose.

(L.42.48.5) The praetor in charge of the fleet, Gaius Lucretius, left Rome with 40 ships of the fleet that had been prepared, his brother Marcus going ahead with one five to collect those due from the allies under treaty, and with orders to meet the rest of the fleet at Kephallenia. These were: one three from Rhegion, two from Lokroi and four from the district of Uria. At Dyrrachion he met ten local , 12 Issaean  and 54 belonging to king Genthios (which Marcus ‘pretended he thought had been assembled for his use’), took them with him ‘on the third day’ to Kerkyra and from there to Kephallenia. (L.42.48.10) Gaius made the voyage from Naples to Kephallenia in five days; and waited there not only until the land force had made the crossing from Italy but also for the supply ships to catch up, ‘which had been scattered from their column over the open sea’. His brother also must have joined him as ordered. Polybios says (27.7) that the Rhodian ships were also summoned at this point.

(L.42.56) Gaius then left the fleet under Marcus’s command with orders to move round the Peloponnese to Chalkis, while, with the intention of getting to Boiotia first, he took a three through the Corinthian gulf, rather slowly ‘because of illness’. Marcus reached Chalkis first and took a large military force, including a substantial Pergamene contingent, inland to besiege Haliartos, where he was joined by his brother coming up from Kreusa on the Gulf. (L.42.63.3 ff) The praetor captured it after a stubborn siege and ‘after these achievements in Boiotia returned to the sea and the fleet’. It is surprising that the ‘maritime province’ exended so far inland.

Other allied ships also assembled at Chalkis (L.42.56.6): two Carthaginian fives, two threes from Herakleia on the Euxine, four from Kalchedon, four from Samos, and then five Rhodian fours. Polybios (27.7.1) describes the mixed reaction at Rhodes to Gaius’s letter, ‘entrusted to a gym trainer’  but finally six fours were sent in support of Rome, five to Chalkis and one to Tenedos, the latter to protect commerce through the straits. The absence of Eumenes and his fleet is not significant, in view of his contribution of land forces and, together with his brother Attalos, his presence with them (L.42.57.4). In the following year his fleet took part in the naval operations off Macedonia.

However, since there was at present no naval activity anywhere, the praetor (P.27.7.16) after receiving kindly all the allies who had come by sea, relieved them of their obligations explaining that in the present state of affairs naval assistance was not required. The legate Quintus Marcius, who after he made his report had been sent back to Greece the previous year with a number of fives (L.42.47.9) and a roving mandate, appeared at Chalkis with his ships, and presumably then returned to Rome.

The assembly at Chalkis of ships of various kinds in support of Rome in 171 is interesting as indicating the standing, economic as well as political, of the various states in naval terms. The piratical  of the Adriatic, from Issa and Illyria, are at the bottom of the table. At the top are the fives of Rome and Carthage, and in between the threes of Herakleia, Chalkedon and Samos. Although Rhodes had fives, the type of ship she used most at this period was the four, from preference probably as Walbank observed (1979: III p. 336) as much as from necessity.

In 170 there is mention in Livy (43.4.8) of an assault by the fleet commander Hortensius, who had succeeded Gaius Lucretius, on the city of Abdera in northern Greece, which, being a free ally of Rome, complained to the senate. (L.43.7.10) Other cities in the area, Emathia, Amphipolis, Maroneia, Ainos, are said to have closed their gates to him. These cities must have been the objects of a naval raid similar to that reported for 169, but, perhaps because of its disreputable nature, not mentioned directly by Livy. There were complaints of the behaviour of Romans in Chalkis and the billeting of seamen in private houses.

At this time the loyalty of Genthios of Illyria was again suspect and (L.43.9.4) eight armed ships (naves ornatae) were sent from Brundisium to the island of Issa where there was a legate in charge with two Issaean ships (probably ) in support. A force of 2000 men, raised locally in that part of Italy, which had been garrisoned the previous year (L.42.36.9), was sent on board the eight ships. The type of ship is not given; they are said to be ‘armed’ in contrast to the . 250 is rather a large number of passengers even for a five used as a troopship, and it has been suggested that ‘8’ may be a scribal error for ‘18’4. The voyage is of 174 sm and at least 30 hours with favourable conditions, say a comfortable two day voyage with a stop for the night halfway on the Italian coast. In more adverse conditions speed would have been more like 4 kn overall, i.e. 45 hours or three days with stops for rest in the middle of the day.

(L.43.12.9 and 15.30) For the campaign of 169 reinforcements for the socii navales were sent, 1500 from Rome and Italy and as many from Sicily. Gaius Marcius Figulus was put in charge of the fleet at Chalkis, which went north in the spring in support of the Roman army in Thessaly and was in sight off the coast (L.44.7.10), but victualling arrangements were less effective, the supply ships having been left further south in Magnesia.

The capture of Herakleia Tracheia by the army (L.44.9.10) in the autumn provided the fleet with a forward base from which Marcius proceeded to ravage the country between there and Thessalonike, the site of the royal dockyards. It was besieged but proved too strongly garrisoned, and he moved north against the second Macedonian naval base, Kassandreia. There he was joined by Eumenes with 20 cataphracts and by five cataphracts from Bithynia. The joint forces besieged the city but abandoned the siege when it was relieved by ten  slipping along the coast at night from Thessalonike. The fleet then retired south to Iolkos for an attack, after ravaging the fields, on the third Macedonian naval base of Demetrias in the gulf of Pagasai, while the army besieged Meliboia 25 miles north (L.44.12.8–13.3) ‘conveniently theatening’ its communications. Both attacks were given up and the army went into winter quarters. While Eumenes took his ships back to Pergamon, Marcius sent part of his fleet to Skiathos for the winter and went with the rest to Oreos (in Euboia) as a good base from which to send supplies to the army in Macedon and Thessaly.

(L.44.17) Concern in Rome for the slow progress of the war in Macedonia led to a more rapid choice of the consul to hold that province, Lucius Aemilius Paulus, and of the praetor in charge of the fleet, Gnaeus Octavius. Aemilius immediately suggested that legates should be sent to Macedonia to inspect the army and the fleet and to report on the loyalty of the allies, the supply position and the achievement of army and fleet in the past year.

Their report severely criticised leadership of the army (L.44.20.2); its present position was dangerous and the supply position critical. Their report on the fleet (L.44.20.6) was that some of the socii navales had died of sickness; that some of them, especially the Sicilians, had gone home, with the result that the ships were undermanned; those in Macedonia had not been paid, and lacked suitable clothes (for the winter); Eumenes’s fleet had come and gone; he, unlike his brother Attalos, seemed wavering in his loyalty to Rome. As a result very substantial reinforcements were ordered for the army and 5000 socii navales for the fleet (L.44.21.11).

During the winter of 169/8 (L.44.23.2–10) Perseus engaged in widespread diplomatic activity, first gaining the formal adherence of Genthios through a special envoy Pentauchos (P.29.3–4) who asked him particularly to prepare for war by sea, since the Romans were entirely unprepared in this sphere in the regions of Epeiros and Illyria and he would be able to carry through easily every scheme he proposed. With Genthios he then approached Rhodes ‘with whom alone at that time resided rei navalis gloria, the prestige of seapower’. He sent letters also to Eumenes and Antiochos.

Perseus also sent his fleet commanders Antenor and Kallippos with 40 , to which were added 5  ( with rams) to protect from Tenedos the ships scattered throughout the Kyklades on their way (from the Black Sea) to Macedon with grain. These ships, launched at Kassandreia, went by way of the harbour under Mt Athos on a calm sea to Tenedos. There they came upon some aphract Rhodian ships under Eudamos which they sent away unharmed. On the other side of the island there were 50 Macedonian grain ships blockaded in a harbour by warships with rams (rostratae) belonging to Eumenes. Antenor promptly moved round and with threats removed the enemy ships. Ten  then convoyed the grain ships to Macedon with instructions to return to Tenedos when they had arrived safely. On the ninth day they rejoined the fleet which was now at Sigeion (at the entrance to the Hellespont).

From Sigeion they made a passage to Sybota, an island lying between Elaia and Chios. Next day they intercepted ‘between the cape of Erythrai and Chios where the strait is narrowest’ 35 horse transports taking Galatian horses and cavalrymen which were being sent by Eumenes from Elaia to Attalos with the Roman army in Macedonia. Eumenes’s commanders had no idea that there was a Macedonian fleet in those waters. ‘But when the lines of the approaching  were clearly visible and the acceleration of the oars and the prows pointing at them showed that enemy ships were approaching, then panic hit them’.

Resistance with ships of that nature was impossible; some who were nearer the mainland swam ashore on Erythraean territory, others raised sail for Chios and ran their ships aground. Abandoning the horses (which it would have taken too long to disembark) they fled in disorder to the city. But since they had disembarked their armed men nearer the city and at a more convenient landing place (commodiore accessu) the Macedonians caught the Galatians and cut them down, some on the road as they fled and others, shut out, in front of the gate. For the Chians, not knowing who were fleeing or who pursuing, had shut their gates. ‘Antenor ordered 20 especially fine horses and the 200 prisoners taken to be conveyed to Thessalonike by the same ten  that had been sent back before’. If the horses were taken on two of the , the remaining eight  would have taken 25 prisoners each. They must have been substantial light craft. He said he would wait for them at Phanai. The fleet moored for nearly three days before the city of Chios and then moved on to Phanai. When the ten  arrived back sooner than they had expected they put out and crossed the Aegean to Delos.

(L.44.29.1) Three Roman envoys who had been sent by the Senate to Alexandria apprehensive of an invasion of Egypt by Antiochos (p. 109) set out from Chalkis in three fives and, arriving at Delos, found there Antenor’s 40  and five fives of Eumenes. ‘The Roman, Macedonian and Pergamene seamen mixed freely under the truce afforded by the sanctity of the place’. Nevertheless Antenor sent his ships out commerce raiding ‘at night mostly in detachments of two or three ships’. His operations had their effect at Rhodes.

At this time (P.29.11 cf. L.44.29.6) envoys from Perseus and Genthios came to Rhodes. The pro-Roman party were ‘dismayed at what was happening. The presence of the  (of Antenor), the size of the (Roman) losses of cavalry (in the previous year) and Genthios’s change of allegiance, were wearing them down’. The Rhodian answer was that they were determined to bring about peace.

In the spring of 168 (L.44.30.1) Aemilius was in Macedon facing Perseus, the praetor Gnaeus Octavius at Oreos with some of the fleet and the rest at Skiathos, and Anicius with Appius Claudius at Apollonia to deal with Genthios. The latter (L.44.30.13–14) had 80  plundering the coast of Epeiros. At 44.30.15 Livy’s text is faulty, but supplemented by Appian (Illyr.9) it appears to indicate that Anicius captured some of Genthios’s ships, defeated him on land and shut him up in a fortress in which he captured him and all his family, thus ending the war on that front (L.45.43.4) ‘in a few days’.

In the meantime (L.44.32.5) Perseus was in great fear not only of the new consul on land but also of the new praetor at sea. ‘He had no less fear of the Roman fleet and the dangerous situation of the sea coast’ as a result of the admittedly often unsuccessful raids in the previous two years. He accordingly diverted forces to strengthen the garrisons of Thessalonike and other cities of the area. (L.44.35.1) When Aemilius was ready to move he planned a feint towards Thessalonike employing the fleet, when his attack was inland. It culminated in the battle of Pydna in which Perseus was heavily defeated and the war brought to an end. (L.44.44.3) Perseus fled to Samothraké from where Octavius brought him to Aemilius at Amphipolis. By this time the end of the campaigning season was reached and the army and fleet went into winter quarters.

As a postscript to the naval war it may be noted (L.45.35.3) that in the following year when Aemilius Paulus returned in triumph to Rome it was on board ‘a royal ship of huge size, which was rowed by sixteen oar-files (versus remorum), up the Tiber to the city’. This was (L.33.30.5) the ‘ship of almost unmanageable size with sixteen oar-files’ which Philip V was allowed to keep after his defeat nearly thirty years before (cf. Plutarch Aemilius Paulus 30.2–3).

(L.45.42.12) Also a number of royal ships seized from the Macedonians ‘of a size not previously seen’ were hauled up on to the Campus Martius. (L.45.43.10) 220  formed part of the booty from Illyria. Genthios seems to have taken seriously Perseus’s advice to concentrate on sea power.