Agis and Cleomenes

Now, there had been agitation among the Achaeans, and their cities were eager for revolt, the common people expecting division of land and abolition of debts, and the leading men in many cases being dissatisfied with Aratus, and some of them also enraged at him for bringing Macedonians into Peloponnesus. Therefore Cleomenes, encouraged by these conditions, invaded Achaea. First, he took Pellené by a sudden assault, and drove out the Achaean garrison; next, he brought over to his cause Pheneus and Pentelcium.

Presently the Achaeans, who were afraid that some treachery was afoot in Corinth and Sicyon, sent their horsemen and their mercenaries out of Argos to keep watch over those cities, while they themselves went down to Argos and began celebrating the Nemean games. So Cleomenes, expecting, as was the case, that while the throng was holding festival and the city was full of spectators, his unexpected approach would be more apt to cause confusion, led his army by night up to the walls,