Odawara Castle is located in Odawara City, Kanagawa Prefecture, Japan (formerly part of Ashigara District in Sagami Province). It is a historically significant flatland-style castle and is one of Japan’s nationally designated historic sites. Once famed as the “impregnable castle of the Kanto region,” it is also known by the names “Komine Castle” or “Kobayakawa Castle.”
Historical Background
The origins of Odawara Castle can be traced back to the late Heian period, initially serving as the residence of local Sagami Province warlord Kobayakawa Tōhira. In the Muromachi period, during the Uesugi Zenshū Rebellion in 1416, the ruling Tōi clan was expelled, and the castle came under the control of the Omori clan, retainers of the Ogigayatsu branch of the Uesugi family.
In 1495, Hōjō Sōun from Izu Province attacked and seized the castle. From then on, Odawara Castle became the base of the Late Hōjō clan, who continuously expanded and fortified it. The castle’s size and defensive capabilities were significantly enhanced. Even in 1561, when the forces of Nagao Kagetora (later known as Uesugi Kenshin) laid siege for a month, the castle withstood the attack, further reinforcing its reputation as “unassailable.”
In 1590, Odawara Castle faced a historic turning point. Toyotomi Hideyoshi launched a campaign against the Late Hōjō clan. Although Hōjō Ujimasa and his son Ujinao chose to defend the castle, they were overwhelmed by Hideyoshi’s vast forces and prolonged siege. After three months, the castle surrendered. Following this battle, Odawara Castle became part of Tokugawa Ieyasu’s domain.
During the Tokugawa period, Ōkubo Tadayo was appointed as the castle lord. Although political shifts later led to the temporary abolition of the castle, it was restored in 1619 when the Abe clan took over. In the 18th century, the Ōkubo clan returned to govern it until the end of the Edo period. In 1871, with the implementation of the abolition of castles decree, Odawara Castle officially ended its role as a military facility.
Architectural Features and Present Condition
Most of the Odawara Castle structures seen today date back to the Edo period, constructed or renovated under the Ōkubo clan. A major renovation in 1632 (Kanei 9) established the castle’s solid stone foundations, which remain among the most iconic parts of the current ruins. Toward the end of the Edo period, three coastal batteries were also installed to defend against foreign threats.
In modern times, Odawara Castle was converted into a public park, serving as a place for leisure and tourism. The main keep (tenshu) was reconstructed in 1960. From the top floor, visitors can view the ruins of Ishigakiyama Ichiyajō on Mount Kasagake. Some historical structures, such as gates and the Akagane-mon (Copper Gate), have also been preserved. Notably, the Great Kanto Earthquake caused damage to the castle’s stone walls, and some traces of this damage remain visible today.
