a strip of land connecting the Crimean Peninsula with the continent. It separates Karkinitskii Bay of the Black Sea from the Sivash. From northwest to southeast the isthmus is 30 km long, and its width is 8–23 km. It has elevations up to 20 m. The isthmus is composed of clays and loams. The coasts are precipitous (up to 5 m). The surface is level, with steppe and semisteppe vegetation. In the southern part of the Perekop Isthmus there are natural salt lakes (Staroe, Krasnoe) at 0.1–4.5 m below sea level. They range in area from 0.5 to 37.5 sq km. The North Crimean Canal runs along the Perekop Isthmus.
In the 15th and 16th centuries, the Turks built strong fortifications, called the Turkish Wall, over the entire isthmus. Russian troops first took the Turkish Wall in 1736 during the Russo-Turkish War of 1735–39. In the Civil War of 1918–20, during the Perekop-Chongar Operation of 1920, the Red Army broke through strong White Guard fortifications on the isthmus and liberated the Crimea. During the Great Patriotic War of 1941–45, Soviet troops waged stubborn defensive actions on the isthmus in September-October 1941. In early November 1943, Soviet troops approached the isthmus from the north, and in April 1944 during the Crimean Operation they broke through the strong fascist German defense there.