(Ἄρατος), of Sicyon, lived from B. C. 271 to 213. The life of this remarkable man, as afterwards of Philopoemen and Lycortas, was devoted to an attempt to unite the several Grecian states together, and by this union to assert the national independence against the dangers with which it was threatened by Macedonia and Rome.

Aratus was the son of Cleinias, and was born at Sicyon, B. C. 271. On the murder of his father by Abantidas [ABANTIDAS], Aratus was saved from the general extirpation of the family by Soso, his uncle's widow, who conveyed him to Argos, where he was brought up. When he had reached the age of twenty, he gained possession of his native city by the help of some Argians, and the cooperation of the remainder of his party in Sicyon itself, without loss of life, and deprived the usurper Nicocles of his power, B. C. 251. (Comp. Plb. 2.43.)

Through the influence of Aratus, Sicyon now joined the Achaean league, and Aratus himself sailed to Egypt to obtain Ptolemy's alliance, in which he succeeded. In B. C. 245 he was elected general (στρατηγός) of the league, and a second time in 243. In the latter of these years he took the citadel of Corinth from the Macedonian garrison, and induced the Corinthian people to join the league. It was chiefly through his instrumentality that Megara, Troezen, Epidaurus, Argos, Cleonae, and Megalopolis, were soon afterwards added to it. It was about this time that the Aetolians, who had made a plundering expedition into Peloponnesus, were stopped by Aratus at Pellene (Plb. 4.8), being surprised at the sack of that town, and 700 of their number put to the sword. But at this very time, at which the power of the league seemed most secure, the seeds of its ruin were laid. The very prospect, which now for the first time opened, of the hitherto scattered powers of Greece being united in the league, awakened the jealousy of Aetolia, and of Cleomenes, who was too ready to have a pretext for war. [CLEOMENES.] Aratus, to save the league from this danger, contrived to win the alliance of Antigonus Doson, on the condition, as it afterwards appeared, of the surrender of Corinth. Ptolemy, as might be expected, joined Cleomenes; and in a succession of actions at Lycaeum, Megalopolis, and Hecatombaeum, near Dyme, the Achaeans were well nigh destroyed. By these Aratus lost the confidence of the people, who passed a public censure on his conduct, and Sparta was placed at the head of a confederacy, fully able to dictate to the whole of Greece, --Troezen, Epidaurus, Argos, Hermione, Pellene, Caphyae, Phlius, Pheneus, and Corinth, in which the Achaean garrison kept only the citadel.-- It was now necessary to call on Antigonus for the promised aid. Permission to pass through Aetolia having been refused, he embarked his army in transports, and, sailing by Euboea, landed his army near the isthmus, while Cleomenes was occupied with the siege of Sicyon. (Plb. 2.52.) The latter immediately raised the siege, and hastened to defend Corinth; but no sooner was he engaged there, than Aratus, by a masterstroke of policy, gained the assistance of a party in Argos to place the Lacedaemonian garrison in a state of siege. Cleomenes hastened thither, leaving Corinth in the hands of Antigonus; but arriving too late to take effectual measures against Aratus, while Antigonus was in his rear, he retreated to Mantineia and thence home. Antigonus meanwhile was by Aratus' influence elected general of the league, and made Corinth and Sicyon his winter quarters. What hope was there now left that the great design of Aratus' life could be accomplished,--to unite all the Greek governments into one Greek nation? Henceforward the caprice of the Macedonian monarch was to regulate the relations of the powers of Greece. The career of Antigonus, in which Aratus seems henceforward to have been no further engaged than as his adviser and guide, ended in the great battle of Sellasia (B. C. 222), in which the Spartan power was for ever put down. Philip succeeded Antigonus in the throne of Macedon (B. C. 221), and it was his policy during the next two years (from 221 to 219 B. C.) to make the Achaeans feel how dependent they were on him. This period is accordingly taken up with incursions of the Aetolians, the unsuccessful opposition of Aratus, and the trial which followed. The Aetolians seized Clarium, a fortress near Megalopolis (Plb. 4.6.), and thence made their plundering excursions, till Timoxenus, general of the league, took the place and drove out the garrison. As the time for the expiration of Aratus' office arrived, the Aetolian generals Dorimachus and Scopas made an attack on Plarae and Patrae, and carried on their ravages up to the borders of Messene, in the hope that no active measures would be taken against them till the commander for the following year was chosen. To remedy this, Aratus anticipated his command five days, and ordered the troops of the league to assemble at Megalopolis. The Aetolians, finding his force superior, prepared to quit the country, when Aratus, thinking his object sufficiently accomplished, disbanded the chief part of his army, and marched with about 4000 to Patrae. The Aetolians turned round in pursuit, and encamped at Methydrium, upon which Aratus changed his position to Caphyae, and in a battle, which began in a skirmish of cavalry to gain some high ground advantageous to both positions, was entirely defeated and his army nearly destroyed. The Aetolians marched home in triumph, and Aratus was recalled to take his trial on several charges,--assuming the command before his legal time, disbanding his troops, unskilful conduct in choosing the time and place of action, and carelessness in the action itself. He was acquitted, not on the ground that the charges were untrue, but in consideration of his past services. For some time after this the Aetolians continued their invasions, and Aratus was unable effectually to check them, till at last Philip took the field as commander of the allied army. The six remaining years of Aratus' life are a mere history of intrigues, by which at different times his influence was more or less shaken with the king. At first he was entirely set aside; and this cannot be wondered at, when his object was to unite Greece as an independent nation, while Philip wished to unite it as subject to himself. In B. C. 218, it appears that Aratus regained his influence by an exposure of the treachery of his opponents; and the effects of his presence were shewn in a victory gained over the combined forces of the Aetolians, Eleans, and Lacedaemonians. In B. C. 217 Aratus was the 17th time chosen general, and every thing, so far as the security of the leagued states was concerned, prospered; but the feelings and objects of the two men were so different, that no unity was to be looked for, so soon as the immediate object of subduing certain states was effected. The story told by Plutarch, of his advice to Philip about the garrisoning of Ithome, would probably represent well the general tendency of the feeling of these two men. In B. C. 213 he died, as Plutarch and Polybius both say (Plb. 8.14; Plut. Arat. 52), from the effect of poison administered by the king's order. Divine honours were paid to him by his countrymen, and annual solemnities established. (Dict. of Ant. s. v. Ἀράτεια.)