Dodecanese islands were occupied by the French and British, but Rhodes remained under Italian occupation. In 1915, the French also occupied Kastellorizo. Following the war, the Tittoni–Venizelos agreement, signed on July 29, 1919, called for the smaller islands to join with Greece, while Italy maintained control of Rhodes. The treaty further outlined an exchange where Italy would receive Antalya for southwest Anatolia. The Greek defeat in the Greco-Turkish War and the foundation of modern Turkey prevented the exchange. Italy formally annexed the Dodecanese as the "Possedimenti Italiani dell'Egeo" under the terms of the Treaty of Lausanne. Mussolini embarked on a program
Symi the peculiarly colorful neoclassical mansions covering the slopes near the main city date from that period. Although Symiots took part in the Greek War of Independence of 1821–1829, it was left out of the new Greek state when its borders were drawn up and so remained under Ottoman rule. The island, along with the rest of the Dodecanese, changed hands several times in the 20th century: in 1912 the Dodecanese declared independence from the Ottomans as the Federation of the Dodecanese Islands, though they were almost immediately occupied by Italy. The island was formally ceded to Italy in 1923, and