Also read edajiro 枝城. Also hajō 端城. Lit. "branch castle." A fortification, other than the main castle, established at an important location within a domain. The main castle was called *honjō 本城 or *nejiro 根城. When the domain was large, several branch castles were established and numbered: "first branch castle" daiichi shijō 第一支城; "second branch castle" daini shijō 第二支城 and so on. During the Warring States period, each domain built a network of branch castles. The lord and his chief retainers were placed in the first branch castle, while his vassals were placed in the second branch castle. The architecture of branch castles varied according to their function. Types included those built primarily for: border defense; liaison; offense; general defense; and management of domain affairs.