The Athenians, on a new high after the Persian war, founded the Confederation of Delos, also called the Delian League, in 477. The purpose of the League was to protect against another invasion from Persia. Most of the Ionian islands joined. Many of the islands were too small to furnish ships themselves, so instead they gave money to the League treasury, kept on Delos, and the Athenians used this money to build ships to protect all the League members.