Why Croatia is a crescent

A country around another

Croatia is crescent-shaped. Its upper arm runs east along the plains of Slavonia to Serbia; the body of the crescent is a long strip of Adriatic coast that reaches south to Montenegro. Inside the hollow lies Bosnia and Herzegovina, which even cuts southern Croatia off from the rest by reaching the sea in a narrow corridor.^[1] The Sava forms most of the border along the inside of the arm, and the coast, with its 1,100 islands and islets, runs about 1,800 km.^[1]

The country is made of three historic regions, Croatia-Slavonia, Istria and Dalmatia, which were ruled for centuries by different foreign powers.^[1] The line between them and Bosnia is, for the most part, an old imperial frontier.^[2][3]

Where the Ottomans stopped

The war that began with an Ottoman march on Vienna in 1683 ended with the peace signed at Sremski Karlovci (Karlowitz) on 26 January 1699, on the rule that each side kept what it held. The Ottoman frontier with the Habsburgs drew back to the Sava and Una rivers: the Habsburgs gained all of Slavonia and Croatia up to the Una, but a large part of medieval Croatia stayed in the Ottoman province of Bosnia.^[2]

On the coast, Venice kept the inland towns it had conquered, such as Knin, Sinj and Vrgorac, and the name Dalmatia spread to them. The Republic of Dubrovnik, wanting no border with Venice, asked for strips of Ottoman land on either side of it, at Neum and Sutorina.^[2] After another war, the peace of Passarowitz (Požarevac) of 21 July 1718 pushed Venetian Dalmatia inland to Imotski and the Cetina valley, along the ridges of the Dinara and Kamešnica mountains, and confirmed the corridors.^[3] The peace of Sistova (Svištov) of 4 August 1791 changed the line with Bosnia only slightly, moving a few forts near the Plitvice Lakes to the Habsburg side.^[5]

From frontier to border

After 1945 Croatia and Bosnia and Herzegovina were two republics within socialist Yugoslavia.^[4] When Croatia declared independence on 25 June 1991, the border between them became an international one, and the crescent became the shape of a country.^[4][1]