This book discusses the intelligence methods and techniques in the Ottoman state, compiled from Ottoman and Turkish sources. With the complete loss of these records in Arabic, it's widely known that after Sultan Abdul Hamid II was deposed, all related files and archives were burned. Thus, there is a significant gap in Ottoman history regarding this subject in particular. This work took two years to gather all available intelligence information from its inception until the establishment of the Yildiz Agency, developed by Sultan Abdul Hamid II, which played a crucial role in the survival and continuation of the Ottoman state for over 33 years when it was on the verge of collapse.