The new colony was conceived as a fully independent state from day one. The foundation decree of Cyrene (Box 5.1) shows that the colonists ceased to be citizens of Thera with immediate effect (else the decree would not have spoken of the colonists’ receiving their citizenship back if the clause allowing their return were implemented).
Nonetheless, the mother-city had obligations, especially in the early years, to its colony. Thera (see Box 5.1) undertook to provide aid to the colonists at Cyrene for five years and agreed to receive the colonists back if such aid were not forthcoming and the colony had to be abandoned. Colonists occasionally invoked this obligation to aid a colony several centuries after the foundation. Thus Syracuse, founded by Corinth in circa 735 BC, requested help from its mother-city when faced with an invasion from Carthage in the mid-340s BC (Diod. XVI 65) (see chap. 17). Taras, founded by Sparta circa 700 BC, applied to its mother-city Sparta for aid, also in the mid-340s BC (Diod. XVI 62,4) (see chap. 17). In both cases the respective mother-city sent what help it could. Sometimes, moreover, it went the other way round. Chalcidian colonists from the Chalcidice returned to Chalcis to help their mother-city in its war against the Eretrians (Plut. Amatorius, 17).
A colony for its part owed to its mother-city a degree of deference (especially in religious matters - Thuc. I 25) which becomes manifest in particular when a colony founded a colony in its own right. In this case the existing colony applied to its mother-city to send out an oecist for the new colony. The Megar-ian colony of Megara Hyblaea did this when it founded Selinus circa 630 BC (see Box 5.2); so did the Corinthian colony of Corcyra when it founded Epi-damnus towards the end of the seventh century (Thuc. I 24).
This is not to say that relations between a colony and its mother-city were always good. Corcyra and Corinth in particular fell out with one another on several occasions. The tyrant of Corinth, Periander, conquered Corcyra at one point and appointed his son Lycophron as its governor (Hdt. III 48 and 52). Thucydides records a naval battle between Corcyra and Corinth in the midseventh century (Thuc. I 13). Finally, it was Corinth’s and Corcyra’s bitter dispute over Corcyra’s colony Epidamnus that helped touch off the Peloponnesian War (Thuc. I 24sqq.).
For the most part, however, colony and mother-city remained close. Cyrene in the fourth century BC, over three centuries after its founding, offered automatic citizenship to any Theran who chose to settle there. Down to 431 BC,
Potidaea received its annual magistrates from its mother-city Corinth (Thuc. I 56). Miletus and its colony Cyzicus maintained an arrangement of mutual grant of citizenship whereby any Cyzicene who came to Miletus was automatically a Milesian citizen and vice versa (SVA 409, 13-16). When the Achaian colonies in southern Italy (founded probably in the late eighth century) were experiencing civic troubles in the late fifth century, they accepted the advice of a commission sent from Achaia, the tribe-state in the northern Peloponnese which had founded these colonies, and went on to reform their constitutions on the model of that of their founders (Pol. II 39).
This last example, incidentally, shows that although scholars conventionally speak of “mother-cities,” tribe-states could and did found colonies also. The tribe-states of the Western and Eastern Locrians collaborated in founding Locri Epizephyrii in southern Italy in the early seventh century (Pol. XII 5-6); the Eastern Locrians founded the colony of Naupactus on the territory of the Western Locrians in the early fifth (Fornara, Nr. 47).