Most Bosnian-gauge railway lines were built during the Austro-Hungarian Empire. Several 760 mm (2 ft 5+15⁄16 in) gauge railways were planned in order to link the extensive narrow-gauge railways in the Austro-Hungarian Empire with those in Bosnia and Herzegovina. Until the outbreak of the Balkan Wars in 1912 several were constructed. Between World War I and World War II the network was extended significantly, at the end connecting the Adriatic Coast with Belgrade, with the network growing to around 1500 km in length.