Philip V, king of Macedon, son of Demetrius II., born in 237 B. C, died in 179. His father died when he was eight years old, but he did not succeed to the throne until the death of his uncle Antigonus Doson in 220. In the first year of his reign he was brought into the war then raging between the AEtolians and the Achaean league. Marching to Corinth with an army for the support of the latter, he presided over an assembly of the allied states in which war was declared against the AEtolians, and in the spring of 219 entered Epirus, but quickly returned to repel an invasion of the Dardanians. At the close of the year he suddenly showed himself in the Peloponnesus, and in a short campaign defeated an AEtolian and Elean army under Euripidas, captured Psophis, ravaged the Elean plain, and conquered Triphylia. He then suddenly passed over into AEtolia, and took Thermum, the capital of that country, with all its treasures; and then, turning to the Peloponnesus, ravaged Laconia and defeated the Spartans under Lycurgus. In 217 he captured Bylazora in Paeonia, and reduced the Phthiotic Thebes in Thessaly, but finally concluded a peace, by which it was agreed that each party should retain what it possessed.

At this time Philip began to turn his attention to the war then waged in Italy by Hannibal, and after the battle of Cannae sent a messenger to conclude an alliance with the Carthaginian leader; but owing to the ambassador being intercepted by the Romans, the treaty was not made till 215. In 214 his fleet appeared in the Adriatic, took Oricum, and laid siege to Apol-lonia, but was obliged to retreat on the arrival of a Roman force under Laevinus. The next year he took Lissus and reduced the greater portion of Illyria. Meanwhile the character of Philip seems to have undergone a great change. In the beginning of his reign he had not only manifested military talents of a high order, but had been so distinguished for his moderation and generosity that the cities of Crete had placed themselves of their own accord under his protection. But now he quarrelled with Aratus, his former friend and counsellor, and ravaged Messenia with fire and sword. In 211 an alliance was entered into against him by the Romans, the AEtolians, Scer-dilaidas, king of Illyria, and Attalus, king of Pergamus. The war began in 210 and lasted till 205; and upon the whole Philip was successful.

The terms of the treaty concluded with the allies were not much respected by the Macedonian king, who formed an alliance with Antiochus the Great of Syria against Egypt; and having inflicted much injury on the Rhodians, he became involved in a war with them and Attalus. While besieging Chios, he was attacked and defeated by the combined fleet; but in another engagement off Lade he was successful. The allies equipped another fleet, and it was with some difficulty that Philip was able to pass over into Europe in the spring of 200. The Romans, now free from their war with Carthage, declared war against Macedon. In 200 Philip invaded Thrace, took AEnus and Maronea, penetrated into the Chersonese, captured Abydos, and returning entered Attica, nearly surprising Athens; but being foiled in this, he laid waste the country around the city. The following year he defeated the AEtolians, who had joined the Romans. The arrival of Titus Quintius Flami-ninus to take the command of the Roman army soon changed the aspect of affairs. A battle was fought in 197 at Cynoscephalae in Thessaly, in which the Macedonians were defeated with a loss of 8,000 men killed and 5,000 taken prisoners.

A peace was concluded in 190, according to the terms of which Philip was required to give up all his conquests in Europe and Asia, surrender his fleet to the Romans, reduce his standing army to 5,000 men, and pay the sum of 1,000 talents. One of the hostages for the fulfilment of these terms was his son Demetrius. Philip now acted outwardly as a zealous ally of the Romans, assisted them in their war against Nabis, king of Sparta, and subsequently not only refused to join Antiochus, but aided the Romans in their war with that monarch. So thoroughly were they satisfied with his conduct, that the portion of the fine unpaid was remitted, and his son Demetrius was sent home. But after the defeat of Antiochus they grew jealous of Philip, who was strengthening his power in every quarter. He was compelled to give up all his conquests in Perrhsebia and Thessaly, remove his garrisons from the cities of Thrace, and restrict his authority to the ancient boundaries of Macedonia. Demetrius was sent to Rome, and procured such advantageous terms that the jealousy of his brother Perseus was excited. The life of Philip was henceforth embittered by the dissensions between his two sons.

In his domestic administration he also became more cruel, while he was engaged in secret preparations for renewing the war against the Romans. In an expedition into Paaonia, Perseus by means of forged letters induced his father to put Demetrius to death. The unhappy king was now overcome with grief and remorse. He thought he was haunted by the avenging spirit of Demetrius, and not long after died, in his last moments cursing his son Perseus. - Polybius said of Philip, that there were few monarchs of whom more good or more evil could justly be spoken. He was a ready speaker, and possessed great power of repartee. He was exceedingly licentious, and fond of excessive drinking.