This study tries to examine the Ottoman borders in Western Slavonia in both a comprehensive and comparative way by including military, socio-economic, and financial aspects of the frontier organization. Furthermore, the aim of this study is to reveal the location of the network of Ottoman fortresses and their role in defense organization in the Sancak of Zaçasna. The Ottoman defensive strategy in Western Slavonia was based on a chain of fortresses running along two long parallel lines. These lines were initially built on fortresses conquered in the region between 1536 and 1552. This strategy, on the other hand, was later reformed through the construction of new fortifications or the demolition of existing ones. The first defense line stretc...