After Salamis and another Greek victory over the Persian fleet at Mycale, the Ionian cities were freed, and the Delian League was formed under the aegis of Athens. Gradually, the predominance of Athens turned the League effectively into an Athenian Empire. The source and foundation of Athens' power was her strong fleet, composed of over 200 triremes. It not only secured control of the Aegean Sea and the loyalty of her allies, but also safeguarded the trade routes and the grain shipments from the Black Sea, which fed the city's burgeoning population. In addition, as it provided permanent employment for the city's poorer citizens, the fleet played an important role in maintaining and promoting the radical Athenian form of democracy. Athenian maritime power is the first example of thalassocracy in world history. Aside from Athens, other major naval powers of the era included Syracuse, Corfu and Corinth.