The two dates which I wish briefly to discuss are those of the Argive Expedition and of the Atheno-Plataean alliance: they are of cardinal importance for the history of Greek politics in an important but very obscure period. The two questions may be considered as independent, and it is possible to adopt the earlier date for one event, and not for the other (as E. Meyer does), but in my judgment the two events are connected, and the date assigned to the one carries with it the date of the other.

First then as to the date of the attack on Argos and the battle of Sepeia. Before the time of Grote this was always placed circ. 520 B.C. on the strength of the passage of Pausanias (iii. 4), ‘when Cleomenes came to the throne, he at once invaded the Argolid’; his accession is usually placed about 520, and as this date is generally accepted, it is needless to give the reasons for it here. The date of Pausanias is in itself worth very little. It is true that he has information as to the Argive campaign which is not in Herodotus, and which may be derived from some local chronicler; but this information is given in an earlier book (ii. 20), while in iii. 4 he is mainly following Herodotus. It may be noticed, however, that he certainly is supplementing Herodotus from some other source (e.g. the name of the grove of Eleusis, ‘Orgas’), and it is not unnatural to suppose that he had reason for giving a date for the expedition of Cleomenes, which differs from that which at first sight seems to be given by Herodotus; Wernicke writes ‘perverse eum (Cleomenem) initio regni sui id fecisse (Pausanias) dicit,’ but it may well have come from some chronological table (such as the Parian Chronicle).