Carystus was a city-state that refused to join the Delian League. The Athenians were outraged and attacked Carystus and torched the entire city. Athens used this tactic alot as it was said to be better for the league. This way, a Greek city-state could not side with Persia and offer their city as a base, and also could not get the advantages of a persian-free Greece without paying their share. A city-state is a region controlled exclusively by a city. ... Delian League (Athenian Empire), right before the Peloponnesian War in 431 BC. Corcyra was not part of the League The Delian League was an association of Greek city-states in the 5th century BC. It was led by Athens. ... For other uses, see Athens (disambiguation). ...
Carystus, a city on the southern tip of Euboea, was forced to join the League by military actions of the Athenians.
The justification for this was that Carystus was enjoying the advantages of the League (protection from pirates and the Persians) without taking on any of the responsibilities.
Naxos, a member of the Delian League, attempted to secede, and was enslaved; Naxos is believed to have been forced to tear down her walls, lost her fleet, and her vote in the League.