Dodecanese of the major islands under Italian rule back to twelve. Thus, when the Greek press began agitating for the cession of the islands to Greece in 1913, the term used was still the "Dodecanese". The Italian occupation authorities helped to establish the term when they named the islands under their control "Rhodes and the Dodecanese" ("Rodi e Dodecaneso"), adding Leipsoi to the list of the major islands to make up for considering Rhodes separately. By 1920, the name had become firmly established for the entire island group, a fact acknowledged by the Italian government when it appointed the islands' first
Dodecanese territories, occupied all the present-day Dodecanese except for Kastellorizo. After the end of the war according to the Treaty of Ouchy, Italy maintained the occupation of the islands as guarantee for the execution of the treaty. The occupation continued after Italy declared war on the Ottoman Empire (21 August 1915) during the First World War. During the war, the islands became an important naval base for Britain and France; Italy was allied with both nations during World War I. The Dodecanese were used as a staging area for numerous campaigns, most famously the one at Gallipoli. Some of the smaller