Eiroku was an era from 2/28 of 1558 to 4/23 of 1570 (based on the Japanese lunisolar calendar) in the Sengoku period.

The change from the prior era known as Kōji occurred in connection with the coronation of Emperor Ōgimachi.

During this era, Ōgimachi (reign: 1557 to 1586) served as the 106th emperor; Ashikaga Yoshiteru (reign: 1546 to 1565) served as the thirteenth shōgun and Ashikaga Yoshihide (reign: second to ninth months of 1568) as the fourteenth shōgun, and Ashikaga Yoshiaki (reign: 1568 to 1588) as the fifteenth and final shōgun of the Muromachi bakufu.

In the Muromachi period, changes to the names of eras were determined on the basis of consultations between the Imperial court and the Muromachi bakufu.  Even when the shōgun was located outside of Kyōto, the name of the era did not change.  However, in this instance, the name of the era changed following consultation with Miyoshi Nagayoshi after he ousted Ashikaga Yoshiteru (the thirteenth shōgun) from Kyōto and established the Miyoshi administration.  Dissatisfied at not having been informed of this change in advance, Yoshiteru continued to use the Kōji era name and raised arms against Nagayoshi.  Among daimyō, some of them continued to use the Kōji era name while others adopted the Eiroku era name.  At the end of the first year of Eiroku, Nagayoshi and Yoshiteru reconciled so that the Eiroku era name would be recognized as the official era name throughout the country.  This was taken as a last resort to avoid a situation where Yoshiteru would become an enemy of the Imperial court which was controlled at that time by Nagayoshi.

In the seventh year of Eiroku, a year of turbulent change according to the sexagenary cycle, Nagayoshi made a petition to change the name of the era.  At this time, Matsunaga Hisahide was a senior retainer of Nagayoshi and son-in-law of a noble named Hirohashi Kunimitsu whose family was charged with delivering messages to the Emperor, so Nagayoshi had the petition delivered via Kunimitsu.  However, owing to ongoing differences between Nagayoshi and Ashikaga Yoshiteru, Emperor Ōgimachi was concerned that making a change to the era name would escalate into a military conflict in Kyōto and therefore decided not to make a change.  As a result, the era name did not change until after the death of both Nagayoshi and Yoshiteru as well as the temporary cessation of hostilities.  This was led by Ashikaga Yoshiaki (the younger brother of Yoshiteru) who became the fifteenth and final shōgun of the Muromachi bakufu in 1568 with the backing of Oda Nobunaga.

Key events

Eiroku 1 (1558)

On 1/16, Takeda Shingen was appointed the shugo, or military governor, of Kai Province and his lineal heir, Takeda Yoshinobu, appointed as an associate to the three deputy shōgun families (the Shiba, the Hosokawa, and the Hatakeyama).

In the ninth month, Kinoshita Tōkichirō (later Toyotomi Hideyoshi) began to serve under Oda Nobunaga.

On 9/25, the statue of the Amitābha in the main hall of the Zenkō Temple was moved to Kōfu in Kai Province and the Kai-Zenkō Temple was constructed.

On 11/27, Ashikaga Yoshiteru (the thirteenth shōgun) and Miyoshi Nagayoshi reached a settlement.

Eiroku 3 (1560)

On 5/19, Imagawa Yoshimoto was killed in a surprise attack at the Battle of Okehazama after he entered Owari Province.

Eiroku 4 (1561)

During the eighth and ninth months, the Fourth Battle of Kawanakajima occurred.

In the eleventh month, Takeda Shingen of Kai Province deployed to western Kōzuke Province in the Invasion of Western Kōzuke.

Eiroku 5 (1562)

In the summer, a band of kokujin families from Hōki Province including the Nanjō and Yukimatsu clans relied upon support from the Mōri to recover their former territories

Eiroku 6 (1563)

On 4/3, the Battle of Yutokoroguchi occurred in Inaba Province.  Forces of the military governor of Inaba led by Yamana Toyokasu were defeated by the army of Takeda Takanobu.

Eiroku 8 (1565)

On 5/19, the Eiroku Incident occurred.  Miyoshi Yoshitsugu, along with the Miyoshi Group of Three and Matsunaga Hisahide executed a plot to storm the Nijō Castle in Kyōto and kill Ashikaga Yoshiteru, the thirteenth shōgun of the Muromachi bakufu.

On 10/15, Takeda Yoshinobu, the eldest son of Takeda Shingen, launched a rebellion known as the Yoshinobu Incident.

Eiroku 10 (1567)

On 10/11, the Battle at the Giant Buddha of Tōdai Temple occurred.  After conflict between Matsunaga Hisahide and the Miyoshi Group of Three over a one-half-year period, the Tōdai Temple was burned down.

Eiroku 11 (1568)

In the third month, Honjō Shigenaga, a retainer of the Uesugi family of Echigo Province, launched a rebellion.

On 9/16, Oda Nobunaga of Owari Province marched upon Kyōto to install Ashikaga Yoshiaki as the fifteenth shōgun of the Muromachi bakufu.

In the twelfth month, Takeda Shingen of Kai Province invaded the territory of the Imagawa clan of Suruga Province in the Invasion of Suruga.

Eiroku 12 (1569)

In the sixth month, Uesugi Kenshin of Echigo Province and Hōjō Ujimasa or Sagami Province entered into an alliance to solidify their defenses against Takeda Shingen of Kai Province.

In the eighth month, Takeda Takanobu attacked Enya Takakiyo of Ashiya Castle in Tajima Province for colluding with the Oda and Amago forces.

Battles

Eiroku 1 (1558)

Battle of Ukino

Siege of Moji Castle

Eiroku 2 (1559)

Battle of Gōrozaka

Eiroku 3 (1560)

Battle of Norada

Battle of Okehazama

Eiroku 4 (1561)

Shōgunjizōyama

Eiroku 5 (1562)

Battle of Kumeda

Battle of Kyōkō Temple

Eiroku 6 (1563)

Battle of Shinkanō

Battle of Yutokoroguchi

Eiroku 8 (1565)

Battle of Dōhora

Eiroku 9 (1566)

Battle of Kōnohshima

Eiroku 10 (1567)

Battle of Inabayama Castle

Battle of Mifuneyama

Battle of Myōzenji

Battle at the Giant Buddha of Tōdai Temple

Battle of Yasumimatsu

Deployment of the Mōri to Iyo

Eiroku 11 (1568)

Battle of Kannonji Castle

Invasion of Suruga

Battle of Tachibana Castle

Eiroku 12 (1569)

Notable births

Eiroku 2 (1559)

Hirano Nagayasu – bushō, daimyō and one of the Seven Spears of Shizugatake.  In the early Edo period, served as the first head of the Tawaramoto domain in Yamato Province

Eiroku 3 (1560)

Ishida Mitsunari – head of the Five Councilors in the Toyotomi administration and lord of Sawayama Castle in Ōmi Province

Eiroku 4 (1561)

Ii Naomasa (2/19) – bushō, daimyō and one of the Four Heavenly Kings of the Tokugawa.  In the early Edo period, served as the first head of the Hikone domain in Ōmi Province

Fukushima Masanori – bushō, daimyō and one of the Seven Spears of Shizugatake.  In the early Edo period, served as the first head of the Hiroshima domain of Aki and Bingo provinces and the Takaino domain in Shinano Province

Eiroku 5 (1562)

Kasuya Takenori – bushō and one of the Seven Spears of Shizugatake.

Katō Kiyomasa (6/24) – bushō, daimyō and one of the Seven Spears of Shizugatake.  In the early Edo period, served as the first head of the Kumamoto domain in Higo Province

Eiroku 6 (1563)

Katō Yoshiakira – bushō, daimyō and one of the Seven Spears of Shizugatake.  In the early Edo period, served as the head of the Matsuyama domain in Iyo Province and the Aizu-Wakamatsu domain in Mutsu Province

Hosokawa Tadaoki (11/13) – bushō, daimyō and one of the Seven Spears of Shizugatake.  A disciple of the tea master known as Sen-no-rikyū.  In the early Edo period, served as the head of the Kokura domain in Buzen Province in northern Kyūshū

Eiroku 8 (1565)

Koide Yoshimasa – bushō, daimyō.  In the early Edo period, served as the first head of the Izushi domain in Tajima Province and the Kishiwada domain in Izumi Province

Eiroku 10 (1567)

Koide Hideie – bushō.  In the early Edo period, served as a hatamoto.

Date Masamune (8/3) – sengoku daimyō of Mutsu Province.  In the early Edo period, served as the first head of the Sendai domain.

Tachibana Muneshige (8/18) – bushō, daimyō.  In the early Edo period, served as the first head of the Yanagawa domain in Chikugo Province in northern Kyūshū

Eiroku 11 (1568)

Kuroda Nagamasa (12/3) – bushō, daimyō and one of the Seven Spears of Shizugatake.  In the early Edo period, served as the first head of the Fukuoka domain in Chikuzen Province

Notable deaths

On 5/19 of Eiroku 3 (1560) (at the Battle of Okehazama)

Imagawa Yoshimoto – sengoku daimyō of Suruga

Ii Naomasa – a bushō from Tōtōmi Province and retainer of Imagawa Yoshimoto

Matsui Munenobu – a bushō from Tōtōmi Province and retainer of Imagawa Yoshimoto

On 12/20 of Eiroku 6 (1563),

Hosokawa Ujitsuna – last deputy shōgun of the Muromachi bakufu

On 7/4 of Eiroku 7 (1564),

Miyoshi Nagayoshi – sengoku daimyō of the Kinai region and Awa Province

On 5/19 of Eiroku 8 (1565),

Ashikaga Yoshiteru – the thirteenth shōgun of the Muromachi bakufu