Ansei

Overview

Ansei (安政) was a Japanese era name (年号, nengō; "year name") that followed Kaei and preceded Man'en. The era began on 15 January 1855 and ended on 7 April 1860, spanning roughly five years of the late Edo period (1603–1868). The reigning emperor throughout the Ansei era was Kōmei-tennō (孝明天皇).

The era name Ansei was proclaimed in the first month of 1855, during a period of intense domestic turmoil and foreign pressure. Japan had been forced open to Western trade only two years earlier, and the shogunate in Edo was struggling to respond. The Ansei years saw a series of natural disasters, political assassinations, and diplomatic crises that pushed the country toward the upheavals of the 1860s.

What Defined the Era

The Ansei era was defined by the collision between Japan's traditional feudal order and the demands of Western powers. The United States, Britain, Russia, and the Netherlands pressed the Tokugawa shogunate for commercial treaties, while domestic factions split between those who favoured opening the country and those who insisted on expelling the foreigners.

The era also carried a grim nickname: the "Ansei Purge" (安政の大獄, Ansei no taigoku). In 1858 and 1859, the shogunate's senior councillor Ii Naosuke arrested and executed opponents of the treaties, including prominent lords and scholars. The purge deepened resentment against the shogunate and fuelled the movement that would eventually topple it.

Natural catastrophe compounded the political crisis. The Ansei Edo earthquake struck in 1855, followed by a cholera epidemic in 1858 that killed thousands in Edo. These disasters were widely interpreted as signs that the heavens had withdrawn their mandate from the ruling order.

Key Events

The Ansei era opened with the aftermath of the 1854 Treaty of Kanagawa, which had opened two ports to American ships. In 1855, the shogunate established the Nagasaki Naval Training Centre to build a modern navy, inviting Dutch instructors to teach Western naval science.

In 1856, Townsend Harris arrived as the first American consul to Japan. Harris negotiated the Treaty of Amity and Commerce, signed in 1858, which opened additional ports and granted extraterritorial rights to American citizens. Similar treaties followed with the Netherlands, Russia, and Britain in the same year.

The signing of these treaties triggered the Ansei Purge. Ii Naosuke, who had become senior councillor in 1858, moved to suppress opposition and to secure the shogunal succession for the young Tokugawa Iemochi. His crackdown targeted court nobles, daimyō, and samurai intellectuals, executing several and imprisoning dozens more.

The era ended in violence. In March 1860, Ii Naosuke was assassinated outside the Sakurada Gate of Edo Castle by a band of rōnin and Mito samurai. The assassination, known as the Sakurada Gate Incident, marked the beginning of the end for Tokugawa authority. The Ansei era closed the following month.

The Name in Japanese

The era name is written 安政 in kanji. Its kana reading is あんせい, and its romaji is Ansei.

The name breaks down into two characters:

• 安 (あん, an): "peace" or "tranquil". This character appears in words like 安全 (あんぜん, anzen, "safety") and 安心 (あんしん, anshin, "peace of mind"). It carries a sense of calm and stability.

• 政 (せい, sei): "government" or "rule". This character appears in 政治 (せいじ, seiji, "politics") and 政府 (せいふ, seifu, "government"). It denotes the exercise of authority over a state or people.

Together, 安政 reads as "tranquil government" or "peaceful rule". The name was chosen to express a hope for political calm, though the era itself proved to be anything but tranquil. The irony was not lost on contemporaries, who watched the shogunate lurch from crisis to crisis under a name promising stability.

How the Era Name Works

The Japanese era name system, called 元号 (げんごう, gengō), dates back to 645 CE, when the first era, Taika, was proclaimed. An era name is a short phrase, usually two kanji, that marks a span of years under a reigning emperor. In the pre-modern period, era names were changed frequently — sometimes to celebrate an auspicious event, sometimes to ward off misfortune, and sometimes simply on the accession of a new emperor.

The choice of an era name was a formal act. Court scholars would propose candidate names drawn from classical Chinese texts, and the emperor would select one. The name was then proclaimed publicly, and all official documents dated from that moment used the new era name. In the Ansei case, the name was adopted in January 1855, roughly two months after the previous era, Kaei, had ended.

An era name does not necessarily begin on the first day of the year. The Ansei era started on 15 January 1855 and ended on 7 April 1860, when the Man'en era began. This means that the Japanese calendar year 1855 was divided between two eras: Kaei until mid-January, then Ansei for the rest of the year.

In the modern period, the system changed. Since the Meiji era, which began in 1868, each emperor has had a single era name that lasts for the entirety of his reign. The era name is also used as the emperor's posthumous name — thus Emperor Kōmei, who reigned during Ansei, is known by his era name, while the era itself is a separate unit of time. For students of Japanese, the era name system remains essential for reading historical documents, since dates are almost always given in the form "Ansei 2" or "Ansei 5" rather than by Western year.