Habsburg-occupied Serbia refers to the period between 1686 and 1699 of the Great Turkish War, during which various regions of present-day Serbia (which were de jure Ottoman territory) were occupied by the Habsburg Monarchy. In those regions, Habsburg authorities have established various forms of provisional military administration, including the newly organized Serbian Militia. By the Treaty of Karlowitz in 1699, some of those regions remained under the permanent Habsburg rule, while others were returned to the Ottoman Empire.