 As a result of their compulsory military service to the Habsburg Empire during conflict with the Ottoman Empire, the population in the Military Frontier was free of serfdom and enjoyed much political autonomy, unlike the population living in the parts ruled by Hungary.After the Bihać fort finally fell in 1592, only small parts of Croatia remained unconquered.The Ottoman army was successfully repelled for the first time on the territory of Croatia following the battle of Sisak in 1593.