The presence of foreign schools in Ottoman lands goes back to the classical periods of the Ottoman Empire. Foreign schools, whose presence was not given importance and formed solely for the needs of the foreign people, ultimately took an important and dangerous situation as the Ottoman Empire evolved into various political stages as time passed. During and after the Tanzimat Reforms, after which the power balance changed against the Ottoman Empire, the fact that missionary activities increased in the religious, cultural and educational fields for the non-Muslim people increased the polarizations and started a wave of separatism among the non-Muslim public. Foreseeing the danger Abdulhamit II took urgent and rapid precautions, making progresses in education all over the empire primarily in Istanbul. However, these efforts were not sufficient and the foreign schools established by the missionaries continued dangerous political and social activities both in quality and effect. We wanted to take attention to the consequences of these foreign schools which took an important part in the fate of a nation.