Croatia in union with Hungary
After the death of the last member of the Trpimirović dynasty, King Stjepan II, there was a battle for the throne in Croatia, which ended with the election of the Hungarian king, Koloman Arpadović, and the contracting of a personal union with Hungary, which lasted until 1918.
Within the new state union, Croatia retained territorial integrity until the reign of Bela IV (1235–79), who founded Slavonia as a new unit of the Croato-Hungarian Kingdom, in the area which was formerly the Duchy of Lower Pannonia. Its clerical seat was Zagreb. At the same time, the Venetians conquered much of Dalmatia, while the regions by the central courses of the River Vrbas and River Sana belonged to Bosnia. After the Arpadović dynasty died out, a war of succession ensued. The Venetians took the remaining Croatian towns in Dalmatia, while the Bosnian rulers took southern Croatia from the River Cetina to the River Neretva.
In 1309, Croatia came under the rule of Charles I Robert, from the Naples branch of the Anjou dynasty. His son, Louis I (Louis the Great) again united Croatia and Slavonia, seized back the territories occupied by Bosnia (1357) and the Venetians (the eastern shore of the Adriatic from Istria to the Bay of Kotor, in 1358), and enabled economic development and integration processes to take place from the River Drava to the Adriatic Sea.
During the reign of Louis’ heir, in the late 14th and early 15th centuries, a dynastic war developed, of which the Venetian Republic and Bosnia took advantage, again extending their territories into Croatian lands.
It was during this period that Dubrovnik began to arise in the far south of Croatia, built on the foundations of strong maritime, trade and crafts traditions, developing a rich culture, diplomacy, pharmacies and social institutions, and introducing mains water and a sewer system, among other things.
‘The bulwark of Christianity’ (1527–1683)
In the mid-15th century, the Ottomans began to press forward into the Croatian lands, particularly after Bosnia fell under their rule in 1463. Their advance was halted by King Matthias Corvinus (ruled from 1458 to 1490), who built a strong fortification system on the eastern borders of Croatia and Slavonia. However, defences were weakened after a victory by the Ottomans at the Battle of Krbava Field in 1493, in which the Croatian nobility was decimated.
‘The Bulwark of Christianity’. Antemurale christianitatis was the Latin expression used in diplomatic correspondence to describe Croatia (a letter from Pope Leo X sent in 1519 to the Croatian ban Petar Berislavić). Simultaneously, the phrase ‘remnants of the remnants’ (reliquiae reliquiarum) was also used, an abbreviation for the ‘remnants of the remnants of the once great and celebrated Kingdom of Croatia’ (reliquiae reliquiarum olim magni et inclyti regni Croatiae).
Following the death of the last Croato-Hungarian king, Louis II of Jagiellon at Mohács, the Croatian nobles elected Ferdinand I of the Habsburg dynasty as ruler in 1527. He opposed the pretender Ivan Zapolja (John Zápolya) and fought against the Ottomans.
In order to strengthen the defences of Zagreb, the first joint Sabor (Diet) of the Croatian and Slavonian nobility was held in 1558, at which the Croatian lands were politically united.
The Ottoman occupation of Croatian lands was halted at the Battle of Sisak in 1593, and the Habsburgs established the Military Border for defence purposes in the border areas. The Military Border was not reunited with Croatia until 1881.The dissatisfaction of the Croatian nobility with the commandeering of Croatian land, the desultoriness of the Habsburgs in terms of mounting a defence against the Ottomans, and their interference in the authority of the Croatian ban (governor) and the Sabor resulted in a failed anti-Habsburg plot in 1671, led by the bans Petar Zrinski and Fran Krsto Frankapan. The Habsburgs used the opportunity of crushing the plot to introduce absolute power over Croatia and Hungary.