In 1530, theislandswere given by Spain to the Order of Knightsof the Hospital of StJohnofJerusalem ina perpetuallease. Their reign ended when Napoleonconqueredthe islands in 1798.
On the island of Kos, there are the mighty towers ofthe Castle oftheKnightsofStJohn, the medieval orderof holy crusaders who went to Jerusalem but never returned home.