Kassos was populated in Minoan times. It is mentioned in the catalogue of ships by Homer as having taken part in the Trojan War. The island was allied with Athens but was independent until the 2nd Century BC when it came under the rule of Rhodes. Pliny mentions it as "Achne" while other sources call it "Amphe" or "Astrabe".
Kassos came under Roman rule and was later part of the Byzantine Empire. It came under Venetian rule in 1306 and fell to the Ottomans in 1537. Under the Turks, the island maintained a great deal of self-rule while paying taxes to the Porte. The Kassiotes developed a large merchant fleet and great wealth.
At the time of the Greek War of Independence in 1821, the population of Kassos had reached 12,000 souls. The island played a crucial role in the naval operations of the war with its fleet harassing the Ottomans who were trying to supply their forces in mainland Greece. Finally, on June 7, 1824, Turkish and Egyptian forces landed on Kassos and destroyed it. 7,000 Kassiotes were killed or taken hostages to be sold as slaves.
For many years after its destruction, Kassos remained deserted. Finally, its inhabitants started to return but the island never regained its former wealth and position. The London Protocol of 1830 kept Kassos under Turkish rule until 1911 when it was occupied by the Italians. Finally, after World War II, Kassos and the rest of the Dodecanese became part of Greece.
Kassos has five towns all situated in the centre of the island, connected by paved roads. They are: