In the Habsburg state the Croats preserved their internal administration, i.e. their parliament (sabor) and ban as the head of government. However, because of constant wars with the Turks they lost a large part of their national territory, particularly eastern Slavonia, southern Dalmatia, Lika, Krbava and their former capitals, such as Knin and Bihac. Venice took Split, Zadar, Sibenik and other cities, so that only Dubrovnik remained free. At that time, Croatia, together with Hungary, was the vanguard and defender of Central Europe, and its territory on the borders facing Turkey were excluded from the administration of the ban and organized as a defensive cordon, called the Military Frontier, under direct rule from Graz and Vienna.
The Turks took hundreds of thousands of Croats and sold them as slaves in the East, and approximately the same amount fled to Austria, Italy and Czech lands, so that even now there descendants live in these places as Burgenland, Hungarian, Slovakian, Moravian, Romanian or Italian (Molise) Croats. The Turks, and then the administration of the Military Frontier settled thousands of non-Slavic Vlachs and Serbs into their homes. In this manner Croatia lost its territory and over a half of its population. Croatian lands belonged to one of the three great powers of the time: the Habsburgs, i.e. Austria, the part taken by the Turks and the coastal belt under the control of the Venetians. Even after the Turks conquered Constantinople, Bulgaria, Serbia and Bosnia almost without resistance, Croatia and Hungary bled for almost two centuries, but they did not fall. In the struggle against the Turks individual Croats such as Nikola Jurisic and Nikola Zrinski distinguished themselves. Croats were particularly celebrated for their role in the great victory at Sisak in 1593, when together with the Habsburg army they defeated the numerically 384 stronger Turkish forces. This was a fateful victory which was marked throughout Europe. It was also a turning point in the Turkish wars, as after this the Croatian recon9uest began, and this continued until 1791. This began with the defeat of the Turkish siege of Vienna in 1683, and was concluded with the Peace of Karlowitz (Srijemski Karlovci), when all of Slavonia and the Pounje, Pokuplje, Lika and Krbava regions as well as the Venetian hinterland of the Adriatic coast was returned to Croatia.
A part of these newly liberated regions were incorporated by Austria for the extension of the Military Frontier. Austria continued to settle Vlachs from Turkish Bosnia and other countries in this territory. The Croatian parliament never surrendered its rights to this part of Croatia on the border with Bosnia. In 1712 the Croats once more showed their independence when they accepted the so-called Pragmatic Sanction, which stipulated that a female could assume the Habsburg throne. The Hungarians did so later, so that in 1740 Maria Theresa ascended to the throne. However, both she and her son Joseph H tried to take away the status of kingdoms away from these nations through their absolutism, centralization and Germanization. In fear of Vienna, the Croats firmly allied themselves with the Hungarians and Budapest in 1790, and they even ceded a part of their autonomous rights to Hungary. From that time forward, the Croats found themselves in a vice between Vienna and Budapest. Both wanted to turn Croatia into just another one of their regions. In addition to Germanization, the danger of Magyarization also appeared.