The Dardanelles is a narrow strait of water that runs for 61 kilometres. The Dardanelles has always been strategically important because it links the Black Sea with the Mediterranean Sea. At the time of World War I, the Dardanelles was controlled by the Ottoman Empire. Control of the Dardanelles and Bosporus strait by the Ottomans prevented the Russian fleet in the Black Sea from joining the Allied fleet in the Mediterranean. They also prevented the Mediterranean fleet from attacking the Ottoman capital, Constantinople (present-day Istanbul), located on the Sea of Marmara.
The Dardanelles are naturally difficult to negotiate as they resemble a twisted hourglass, and the notorious passage called the Narrows is easily defended from both shores. There are also two currents flowing through the Dardanelles: a surface freshwater current of 1 to 4 knots flowing towards the Aegean Sea, and an underwater current of salt water flowing towards the Sea of Marmara.
The Ottoman Empire added built defences to enhance the Dardanelles’ natural barriers.
By 1915, forts with heavy guns and mobile howitzers were strung along both sides of the mouth near the Aegean. From Kephez Point, the first turn before the Narrows, rows of mines were laid. A single line of mines that was secretly laid parallel to the Asia Minor coast had cut the Allied fleet apart on 18 March, when it first tried to force the strait. Sweeping searchlights were ready to pick out any who might attempt a night attack (Brenchley, F & E 2001, Stoker’s Submarine, p. 55).
The Australian War Memorial website argues that the Gallipoli landings were mounted in an attempt to take control of Ottoman forts and artillery along the Dardanelles’ shores.