Ottoman Hungary
The 17th century brought military defeats on the Ottoman Empire's western frontier. With major wars occurring every few decades, Bosnia was economically and militarily exhausted. The most critical conflict was the Great Turkish War. At its start in the mid-1680s, the Habsburgs conquered nearly all of Ottoman Hungary and sent tens of thousands of Muslim refugees into Bosnia. A similar influx occurred with the Habsburg conquest of Lika and Slavonia. Thousands of Muslims fled eastward into Bosnia, and those who remained were forcibly converted to Catholicism. An estimated 100,000 or more Muslims were expelled from the frontier regions and settled in Bosnia during this time; many brought hostility towards Christianity.