The history of the League of the Islanders is relatively obscure, as no literary sources about it have survived. The only evidence comes from inscriptions. In 314/3 BC,
Antigonus I Monophthalmus sent a fleet under his nephew
Dioscurides to the
Aegean islands, in order to defend them against the fleet of
Ptolemy I and secure their allegiance to his cause. Although a fragmentary inscription from the League of the Islanders, typically dated to 306 BC, is often cited as evidence for the League's foundation, modern scholarship tends to place its establishment in the immediate aftermath of Dioscurides's campaign in 314/3 BC. The League was centred on
Delos and stood under the protection of Antigonus, in whose honour annual games, the
Antigoneia (Ἀντιγόνεια), after 306 BC alternating with games (Δημητρίεια,
Dēmētrieia) in honour of Antigonus' son
Demetrius Poliorcetes, were celebrated. Despite the defeat and death of Antigonus at the
Battle of Ipsus in 301 BC, Demetrius retained control of the Antigonid fleet and thus of the League until , when he was defeated and captured by
Seleucus I. As a result, the islands passed under the hegemony of the
Ptolemaic Kingdom, and the games were renamed as
Sotēria Ptolemaia (Σωτήρια Πτολεμαῖα) and
Philadelphia (Φιλαδέλφεια) in honour of Ptolemy I Soter and his son
Ptolemy II Philadelphus. The islands remained under Ptolemaic control until sometime in the middle of the 3rd century BC. The last documents pertaining to the League date approximately to the second quarter of the century; no
nēsiarchos is attested after , and the number of Ptolemaic offerings to Delos also drops off sharply at the same time. This indicates that the League collapsed, and the Ptolemies lost control of the Aegean, either during the
Chremonidean War (268/7–261) or the
Second Syrian War (260–253). Modern research connects this with the Ptolemaic naval defeats at the hands of the
Macedonians and the
Rhodians at
Cos,
Ephesus, and
Andros—the precise dating of these battles has been heavily disputed among historians, but they are now usually dated to 261 BC, , and 246/5 BC respectively. It appears that when Ptolemaic control was first interrupted, after Ephesus, the Rhodians stepped into the power vacuum, concluding alliances with some of the islands like
Ios. Ptolemaic control was possibly re-asserted to some degree after the end of the Second Syrian War, and a
Ptolemaia festival was once again celebrated in 249 and 246 BC, but the evidence is meager. As the historian Gary Reger writes, the celebration of the festival "can be attributed as much to piety and tradition as to advertisement of political hegemony". At any rate, the Ptolemaic position collapsed completely after Andros, both as a result of the military losses as due to the lack of strategic interest: unlike earlier in the century, when the Cyclades had served as a springboard for interference in the Greek mainland, at this point the Ptolemies had more vital concerns in the
Levant and
Asia Minor to pursue. Consequently, except for
Thera, where they maintained a garrison, the Ptolemies abandoned the central Aegean. Many scholars, like
William Woodthorpe Tarn and
Maurice Holleaux, suggested that the Ptolemaic withdrawal resulted in a Macedonian hegemony over the Cyclades, while others, like Hendrik van Gelder, or P. M. Fraser and G. E. Bean, posited a Rhodian hegemony, either in direct succession of the Ptolemies, or, more often, after the 230s/220s BC. Reger, however, considers that the available
epigraphic and other evidence shows few indications of a Rhodian predominance, while the Macedonian kings seem to have limited their interest to the islands closest to the Greek mainland—Macedonian control is attested for
Andros and possibly
Keos and
Kythnos, with some influence, probably temporary, in
Amorgos and
Paros in the direct aftermath of the Battle of Andros—and the
panhellenic sanctuary at Delos. According to Reger, by and large the individual Cycladic islands appear to have remained free and autonomous for the rest of the century. In the meantime, Rhodes rose to become the chief naval power in the Aegean and even beyond. In order to protect their political and commercial interests, such as the
grain trade, where Rhodes held a dominant position, the Rhodians were active against pirates such as
Demetrius of Pharos or the
Cretan cities and the
Aetolian League; both of the latter secretly sponsored by King
Philip V of Macedon. By , according to
Polybius (
The Histories, IV.47.1), the Rhodians "were considered the supreme authority in maritime matters" and were called upon by merchants to intervene in cases such as the imposition of tolls by the
Byzantines on passage of ships through the
Bosporus. In 201 BC, during the
Cretan War, Philip V of Macedon subdued the Cyclades at the head of his fleet, but already in the next year, the Rhodians took over of most of the islands except for the Macedonian-garrisoned islands of Andros,
Paros, and Kythnos. Followed by further Macedonian setbacks in the
Second Macedonian War (200–197 BC), the Cycladic islands, already bound individually to Rhodes by treaties of alliance, were soon after—an exact date cannot be ascertained—formed into a "Second Nesiotic League" under the hegemony of Rhodes. The motivations for Rhodes' move are unclear, but the historian Kenneth Sheedy has suggested that they stemmed at least partly from a desire to preempt other powers, whether the
Kingdom of Pergamon or the
Roman Republic, from establishing control over the area. Unlike the original League however, the Second League appears to have been a more voluntary association. The Second Nesiotic League is commonly held to have lasted until the end of Rhodian independence at the conclusion of the
Third Macedonian War in 167 BC, but Sheedy suggests that it may have started to disintegrate earlier, as the Rhodians focused their attention on maintaining their grip over their
Asian holdings and could no longer afford to maintain the costly hegemony over the Cyclades. ==Institutions==