Name in Japanese: 観音寺城
Pronunciation: kannonjijō

Mt. Kinugasa is one of the highest mountains rising from the plain east of Lake Biwa. It extends from north to south with a long ridge along its top. At 432 m, it’s significantly higher than its near neighbour, Mt. Azuchi which is only 198 m high. Both mountains were home to the most formidable castles of their time, and you can still see the ruins of the castles today.

In the early days of Buddhism in Japan, many temples were built on mountaintops, both to ensure the seclusion required for religious practice, as well as for defence against hostile forces. On the mountaintop of Mt. Kinugasa was a temple called Kannon-ji, around which the monks built major earthworks.

It’s not known when the temple was converted into a secular fortress, although it’s mentioned in the Taiheiki historical chronicle as a base during the period of the Northern and Southern dynasties in 1335. It was the base castle of the Sasaki clan of the Ōmi Genji, and later of the Rokkaku clan, military governors of Ōmi. It was part of a network of castles with Wadayama Castle, Saso Castle, Mitsukuri Castle, and Chōkōji Castle as subsidiary bases.

On the slope on the southern end there was an earthwork enclosure where residences of vassals and provincial lords were arranged. It was unique among medieval castles in having many stone walls, even before the later Azuchi Castle, which is considered innovative for its defences all of stone. In the period from 1530 to 1550, a castle town was established, and a public market was held at a temple there. In the area surrounding the castle was Lake Biwa and the Dainaka Lake, the Tōsandō Road from Mino to Kyōto, and the Happū Kaidō Road linking the Chōkōji settlement and Ise. Consequently the castle was well-positioned to control these strategic thoroughfares.

The castle occasionally changed hands in fighting between factions of the Rokkaku Clan who were supporting different factions in the Imperial and Shogunal conflicts from the 1300s to 1500s, and the castle was the scene of several sieges. In 1532, the castle was substantially renovated to welcome Ashikaga Yoshiharu, the twelfth Shogun. A poet who visited the castle in 1544 was served tea with elegant utensils from China in splendid surroundings. In 1550, additional stone walls were built in response to the advent of guns, and the castle was provided with small cannons.

In 1568, when Oda Nobunaga led an army to Kyoto in support of Ashikaga Yoshiaki, the Rokkaku clan opposed him. When the subsidiary Mitsukuri and Wadayama Castles fell to Nobunaga, the Rokkaku fled Kannonji Castle and it fell to Nobunaga bloodlessly. Nobunaga appears to have used the castle himself for a while, before building an imposing castle in a more modern style in 1576, on Mt. Azuchi, a small mountain adjoining Mt. Kinugasa to the west.

Although Kannonji Castle was one of the largest castles in Japan, apparently it lacked basic defences such as simple hardened gateways or vertically oriented ditches. Consequently it’s inferred that the castle had a more political than military function. The defensive strategy of the Rokkaku during the Warring States period was to intercept external enemies at a perimeter extending far from the castle. From an attack in 1496 to the defeat by Oda Nobunaga, the castle was not attacked by an external enemy for seventy years. When the Rokkaku clan were occasionally forced to surrender the castle, rather than undertaking full-scale sieges, they rebuilt their power and retook it using various stratagems, until Nobunaga finally deprived them of their territory.

There are several hiking trails up and across the mountain. One route starts at Kuwanomi Temple near the Azuchi Archaeological Museum, and follows a long series of stone steps, arriving in the middle of the castle ruins. There’s a 300-yen charge to see the temple and use this route. Another path goes up a long flight of stone steps from Hiyoshi Shrine to the impressive Kannonshō-ji Temple, from whence the path continues up to the ruins. A further hiking trail goes up the southeastern flank of the mountain and follows the ridge down at the northern end, taking in many of the salient features of the castle remains.

The ruins of the castle are designated as a national historical site, although the ruins are very poorly signposted. Impressive stone walls are distributed in areas corresponding to the main enclosure and the residences of the lord and his main vassals. On the south side of the hill, there’s a high wall topped with a level area where tall white banners flap and snap in the breeze. A magnificent view extends for tens of miles, encompassing other castle sites such as Chōkōji. At frequent intervals, bright white Shinkansen trains cross the plain with a roaring sound.