The Treaty of Lucerne (1920) had demilitarised the Straits (Bosporus and Dardanelles) and opened them to unrestricted civilian and military traffic, under the supervision of the International Straits Commission (IST-CID) of the League of Nations (LoN). The IST-CID also administered and supervised the Free Zones.
The International Straits Commission (IST-CID)
The Commission (IST-CID) is composed of a representative of Ottoman Empire (suspended, resumed in 1930 by the Republic of Turkey), who was the President, and representatives of France, Great Britain, Italy, Japan, Bulgaria, Greece, Romania, Russia (suspended, representation re-assumed in 1931 by FSR), and Austria-Hungary.
The United States of America, in the event of their acceding to the Treaty, would also be entitled to have one representative in the IST-CID.
The Straits Commission carried out its functions under the auspices of the LoN, and addressed to the League an annual report giving an account of its activities, and furnishing all information which might have been useful in the interests of commerce and navigation; with this object in view the Commission also place itself in touch with the departments of the Turkish Government dealing with navigation through the Straits.
The free zones
The free zones, were certain ports declared to be of international interest. The LoN, by the IST-CID, was in charge of supervising the completely free and absolute equality in treatment, particularly in the matter of charges and facilities ensuring the carrying out of the economic provisions in commercially strategic places.
These ports (or free zones) were: Istanbul (from St. Stefano to Dolmabahce and Haidar-Pasha), Smyrna, Güllük, Antalya, Mersin, and Alexandretta.
The other free zones, Trabzon and Batum, were each occupied and administered by the Turkish Republic of Pontus and Transcaucasia. Fruitlessly the IST-CID several times communicated the occupying states to relinquish their control and return it to the Commission.
Relationship IST-CID and Turkey
The Turkish government never accepted the terms of the Treaty of Lucerne. In the protests or obstruction of the work of the IST-CID, it always issued a declaration calling for the full resumption of Turkish military control over the Straits and the refortification of the Dardanelles. During the Third Balkan War the Turkish government dispatched a lengthy diplomatic note to the signatories of the Treaty of Lucerne proposing a conference on the agreement of a new regime for the Straits and requested that the LoN authorize the reconstruction of the Dardanelles forts.
The Turkish government specially blocked and obstructed the supervision of the free zones in Istanbul, an later when it gained its territorial control, the ports of Smyrna, Güllük, Antalya, and Mersin. The usual means of protest was by ignoring or delaying the instructions, or sending back for consultation the decisions of the IST-CID or a boycott of port activities. In regard to the Straits, officially named Turkish Straits, it complained of its demilitarization and usually as a means of protest declared vacant its delegate to the IST-CID, and therefore the Presidency, for weeks or months time.