Dodecanese relative quiet and prosperity. In 408 BC, the three cities of Rhodes had united to form one state, which built a new capital on the northern end of the island, also named "Rhodes"; this united Rhodes was to dominate the region for the coming millennia. Other islands in the Dodecanese also developed into significant economic and cultural centers; most notably, Kos served as the site of the school of medicine founded by Hippocrates. However, the Peloponnesian War had so weakened the entire Greek civilization's military strength that it lay open to invasion. In 357 BC, the islands were conquered by
Kasos island formally joined the Kingdom of Greece on 7 March 1948 together with the other Dodecanese islands. Kasos Kasos (; , ), also Casos, is a Greek island municipality in the Dodecanese. It is the southernmost island in the Aegean Sea, and is part of the Karpathos regional unit. , its population was 1084. The island is known in Italian as "Caso". Kasos lies southwest of Karpathos, between this island and Crete. Adjacent to the island is the Strait of Kasos, through which some of the Modified Atlantic Water enters the Sea of Crete. Its shape is elliptic and resembles