Mizuki

Overview

Mizuki (水城, みずき, Mizuki) is an ancient Japanese fortification in Fukuoka Prefecture, built in 664 during the Asuka period (538–710), in the fourth year of the Hakuhō era (白鳳, はくほう). It is classed as a castle and is counted among the Continued Top 100 Japanese Castles (続日本100名城, Zoku Nihon Hyaku Meijō). The earthwork straddles the borders of the cities of Ōnojō, Dazaifu and Kasuga in Fukuoka Prefecture. It is also described as a Korean-style mountain castle (朝鮮式山城, Chōsen-shiki yamajiro), a category of fortification built on continental models. Its ruins have been protected as a National Historic Site since 1921, were raised to Special National Historic Site status in 1953, and the protected area was expanded in 2013.

History

Mizuki was built in 664, the year after the battle of Hakusukinoe. Japan had sent an army to the Korean peninsula to support the kingdom of Baekje against the allied forces of Tang China and the Korean kingdom of Silla, and that army was destroyed in 663. The defeat left the Yamato court exposed to the possibility of invasion from the continent, and Mizuki was one of the measures taken in response.

The fortification was raised on the plain inland from Hakata Bay, guarding the landward approach to Dazaifu (大宰府, だざいふ), the administrative headquarters through which the court governed the whole of Kyushu. Rather than a hilltop stronghold, Mizuki was an earthwork: a long rampart thrown across the route, with a water-filled moat in front of it. The design belongs to the Korean-style mountain castle tradition, fortifications built on continental models imported from the Korean kingdoms.

The work dates to the fourth year of Hakuhō, an era name (年号, nengō) used in the Asuka period. The site's importance was recognised in the modern era when it was designated a National Historic Site in 1921. In 1953 the designation was raised to Special National Historic Site, and in 2013 the protected area was expanded. Its inclusion in the Continued Top 100 Japanese Castles reflects its standing among the country's historic fortifications.

What Stands There Today

What survives at Mizuki is the earthwork itself: the line of the rampart and the trace of the moat, preserved as a historic site rather than as standing buildings. The site is known as Mizuki-jō ato (水城跡, みずきじょうあと), the "Mizuki castle ruins", and its protection as a Special National Historic Site covers the earthwork and its surroundings. The remains lie across the boundaries of three cities — Ōnojō, Dazaifu and Kasuga — so the protected area is spread over more than one municipality.

The Name in Japanese

The name is written 水城. Its kana reading is みずき, and its romaji is Mizuki.

The first character is 水, read mizu in this word. It means "water". The second character is 城, read ki here. It means "castle" or "fortress". The same character appears in the word for castle, 城 (しろ, shiro), and in the names of fortifications across Japan; its reading shifts to ki in compounds such as this one.

Taken together, 水城 means "water castle" or "water fortress". The name fits the structure: the moat was a defining part of the defences, and the rampart was built to hold a body of water in front of it. The reading みずき is irregular in the sense that 城 is normally read shiro or jō when it stands for a castle, so the name is worth learning as a set phrase rather than assembled from its parts each time.

The site name used in signage and official designations adds 跡 (あと, ato), "ruins" or "site", giving 水城跡 (みずきじょうあと, Mizuki-jō ato). Note that 城 is read jō in that compound, following the ordinary Sino-Japanese reading for castles.

Visiting and Context

Mizuki lies in Fukuoka Prefecture, on the plain behind Hakata Bay and close to Dazaifu, the old administrative centre of Kyushu. Its position explains its purpose: it guarded the inland approach to Dazaifu rather than a mountain pass or a coastline. The site is protected as a Special National Historic Site, with the protected area expanded in 2013, and it is listed among the Continued Top 100 Japanese Castles.

For readers of Japanese, the site offers a compact lesson in how the language names fortifications. The word 城 carries the meaning "castle" whether it is read shiro, jō or ki, and the three readings appear side by side in the site's own name: 水城 (みずき) for the fortification, 水城跡 (みずきじょうあと) for its ruins. The era name Hakuhō (白鳳, はくほう) and the period name Asuka (飛鳥, あすか) belong to the same early layer of Japanese historical vocabulary, and both appear in the standard accounts of the site.