Besides periods of small-scale borderland warfare, the conflict also saw episodes of major conquest campaigns of Croatian land undertaken by the Ottomans especially during the 16th century.[24] In the fall of 1463, Corvinus led an army and captured parts of northern Bosnia and towns along the Vrbas and Usora rivers, including the fortress of Jajce in December, after a three month siege.[30] The mountains and forests of medieval Croatia provided cover for Ottoman raiding parties, enabling them to remain longer on Croatian territory.At that point the presence of captives which akinjis would capture as well as the heavy booty which they carried back made their return more slow and therefore vulnerable to the enemy attack such as at Battle of Una in 1483.According to Croatian historian Ivan Jurković, danger zones affected by possible akinji raids could be graded in three levels: In the aftermath of fall of medieval Kingdom of Bosnia to the Ottomans in 1463, Hungarian king Matthias Corvinus established the banates of Jajce and Srebrenik, which formed the centre of his new defense system.[16] Although incursions of Ottoman akinjis were usually successful,[40] the forces of the Croatian ban and local nobles sometimes intercepted these raiding groups on their way back to Ottoman-held territory.[16] Despite everything mentioned earlier, the Ottoman danger did not stop internal conflicts between Croatian and Slavonian nobility, which further undermined an efficient defense.[20] In 1483, an army led by Croatian Ban Matthias Geréb destroyed the Ottoman raiding party in Battle of Una near Novi Grad.[43] By that time, the constant warfare left many villages deserted, and almost completely stopped the major trade route between Senj and Zagreb and inward towards Hungary.As this was taking place, news of another Ottoman raiding party returning through Croatia towards Bosnia in August, forced them to quickly conclude truce and quit the siege.[46] Derenčin, gathered an army consisting of a number of Croatian nobles and their units and attempted to block the Ottoman path back to Bosnia.He decided to face the Ottoman army in an open battle, although Croatian nobles unsuccessfully insisted that making an ambush in the mountains would be a better option.On 9 September, the Croatian army clashed with the Ottoman forces near Udbina in Lika and suffered a huge defeat in the battle of Krbava Field.[58][59] The loss of Knin gave more momentum to the Ottoman advance, while leading role of Croatia's defenses south of the Sava River fell to Bihać.[60] Following the fall of Knin and Skradin, Habsburg supreme military commander Nicholas, Count of Salm arrived to Croatia to consult with Karlović about further defense from the Ottomans.[61] Karlović resigned from position of Croatian ban in 1524 because permanent state of war against the Ottomans caused all of his possessions to get ravaged, which impoverished him severely.In ensuing interregnum Croatia and Hungary became disputed territories between Ferdinand I of the House of Habsburg, and John Zápolya, Voivode of Transylvania.[63] Croatian nobility continuously asked him to invest in both reconstruction of fortifications on the borderlands towards the Ottoman Empire and send actual troops to man them.[63] As the civil war for the Hungarian crown between Ferdinand Habsburg and John Zapolya raged, the Ottomans used the instabilities to further capture Croatian forts in Obrovac, Udbina, Komić and Mrsinj and by which they asserted their control over entire Krbava county and made ground for further advances to Lika.[65] In 1537, after prevailing over Zapolya in Civil War and as a result of continuous pressure from the Croatian nobility, Ferdinand Habsburg named one of his seasoned commanders Johann Katzianer as supreme royal captain "of our Slavonian kingdom" on joint Croatian-Slavonian parliament held in Križevci in spring of 1537.[66] An army of 24 000 men assembled near Koprivnica and marched off to Slavonia in order to chase away the Ottomans, with their main objective being town of Osijek.[69] Carinthian, Carniolan and Styrian nobility agreed to partially finance the Military Frontier in order to hold off the Ottomans in Croatia/Slavonia and therefore prevent them from invading their own lands.[73] Croatian-Slavonian parliament also decided to recruit 300 strong haramija force in order to counter frequent Ottoman martolos raids.[6][78] Same year in spring, Ottomans constructed pontoon bridges over Sava river near Gradiška and started amassing troops in Banja Luka.A Habsburg relief army under the supreme command of the Styrian general Ruprecht von Eggenberg, was quickly assembled to break the siege.Even though the Ottoman defeat near Sisak in June triggered the start of Long Turkish War, by the end of it, the Habsburgs managed to achieve a rather favourable peace treaty in 1606.[6] According to Croatian historian and turkologist Nenad Moačanin, the failure of Hasan Pasha's offensive and his death near Sisak ushered in the period of the 17th century which was characterized by relative stability of Croatian-Ottoman border.[6] Although the Croatian Kingdom suffered major defeats in battles, it remained in existence, keeping its identity, religion, and culture under the Habsburg monarchy.[84] The news of the Croatian defeat on Krbava also reached the Windsor court of English king Henry VII Tudor, after being informed by the pope Alexander VI in one letter.
Hungarian and Croatian king
Matthias Corvinus
formed two defensive provinces called "banates" following the fall of Bosnia and his
recapture of Jajce fortress in 1463
. The purpose of Banate of Jajce was defense of Croatia against the Ottoman incursions. The Jajce banate is shown in bright orange color on the map.
Udbina Castle
, seat of Croatian ban
Ivan Karlović
, as it was in around 1530. Depiction from Venetian cartographer Matteo Pagano.
The
Cetin Charter
from 1 January 1527 which confirms the election of Ferdinand Habsburg on position of king of Croatia. The charter shows seals of most distinguished Croatian nobles as well as seal of Croatia.
A map of 1537 Katzianer's Campaign.
A town of
Karlovac
was founded in 2nd half of the 16th century, to serve as a strongpoint in defense against the Ottomans. This picture shows Karlovac star shaped renaissance fort.
Map of
Croatia
(orange) and Ottoman expansion at the beginning of 1576
Sisak fort
, where final battles of Hundred Years' Croatian–Ottoman War took place.