Goryokaku belonged to the Tokugawa shogunate's broader effort to defend the Tsugaru Strait and northern Japan against possible Russian attack. Its artillery, infantry, and strong fortifications were intended to force an invader into a costly siege and buy time. The delay would give the shogun a chance to gather forces from across the domains and mount a centralized counterattack. The plan reveals both serious investment in modern defence and the weakness of relying on many regional forces to respond in unison. The civil war exposed that institutional problem when a unified reaction could no longer be assumed.
Notable Point · 38:59-41:10
Goryokaku and the shogunate's defence-in-depth system
The star fort at Hakodate was built to delay a Russian landing long enough for Japan's decentralized forces to assemble a response.