The Persian threat prompted this alliance of Greek states, with headquarters on the island of Delos. Athens assumed the leadership of the League.
Citation:
Bouchard, Elsa. "Formation of the Delian League".
The Literary Encyclopedia. First published 01 March 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=11195, accessed 26 May 2013.]