The Athenian expedition led against Macedonia by Archestratos, son of Lykomedes, early in 432 was not diverted from its destination by the revolt of Poteidaia. Archestratos had received additional instructions to enforce the Poteidaia ultimatum if he could, but, this being already impossible, he continued with the real object of his mission, the attack on Perdikkas II of Macedon. The widespread revolt among the Chalkidians had deprived the Athenians of the bases for this attack on which they might have reckoned, and Archestratos had at the outset to make good this loss by recapturing Therme, at the head of the gulf to which it gave its name. Therme, or Serme, had been a tributary member of the Delian League since 450/449:2 it need not necessarily be said that it lay within Macedonia, as Poppo and Bergk inferred from Thucydides 1. 61. 2, but it is at least likely that it lay on the boundary, as it was handed over to Perdikkas under the agreement of 431 (Thuc. 2.29.6).3 However, that the Athenians could include in their Empire a city within Macedonian territory is shown from the position of Berge (tributary since 452/451), and is likely in other cases, e.g. Haison. From Therme, Archestratos moved on to Pydna, presumably by sea, and laid siege to it. Here he was joined by substantial reinforcements, while at the same time the situation in Chalkidike became increasingly embarrassing, so that a peace and a reinsurance alliance were seen by both sides to be ‘imperative’ (Thuc. 1. 61. 3). When these had been concluded, the Athenians moved against Poteidaia.