Igi Tadatsugu served as a bushō from the Sengoku to early Edo periods.  He was the first head of the Igi family.

In 1543, Tadatsugu was born as the son of Kagawa Shichiemon in Kiyosu in Owari Province.  He was initially called Kagawa Chōbei (or Seibei) and served the Oda clan.

Tadatsugu participated in the invasion by Oda Nobunaga of Mino Province and, in 1561, served valorously during an attack against Saitō forces located on Mount Igi across a river from Inuyama Castle.  For these contributions, he was granted the Igi surname and permitted to build a castle on Mount Igi, whereupon he resided in Igiyama Castle.  Upon the wishes of Ikeda Tsuneoki, a senior retainer of Nobunaga tasked with shoring-up the band of retainers, Tadatsugu was solicited by Moridera Hidekatsu (a retainer of Tsuneoki) and he then entered into service for Tsuneoki.  He is deemed to have become a retainer in 1560 or 1561, but the year is uncertain.

On 6/2 of Tenshō 10 (1582), Nobunaga unexpectedly died in a coup d’état known as the Honnō Temple Incident.  Thereafter, Tadatsugu’s lord, Tsuneoki, joined the camp of Hashiba Hideyoshi and was active in the Battle of Yamazaki and the Kiyosu Conference to determine the successor to Oda Nobunaga.  In 1583, Tsuneoki became the lord of Ōgaki Castle in Mino with a fief of 130,000 koku.  After the head of the senior retainers, Moridera Hidekatsu, fell ill, Tadatsugu served in his place as a key figure in the Ikeda family.

In 1584, in the prelude to the Battle of Komaki-Nagakute, the Ikeda family struggled to decide whether to align with the Hashiba or the allied forces of the Oda and Tokugawa.  Citing his connections to Hideyoshi and for the prosperity of their descendants, Tadatsugu advocated for the support of Hideyoshi.  At the outset of fighting, Tsuneoki attacked Inuyama Castle, then stopped at Jōjō Castle, and, together with Miyoshi Nobuyoshi (later known as Toyotomi Hidetsugu), Mori Nagayoshi (Tsuneoki’s son-in-law), and Hori Hidemasa, attempted to attack Tokugawa Ieyasu’s main base in Mikawa Province.  In the first half of the battle, a bullet struck Tsuneoki’s saddle, causing him to fall from his horse and, along with Nagayoshi, he died in battle at Nagakute after being stabbed by a spear wielded by Nagai Naokatsu.  His eldest son, Ikeda Motosuke, was also killed in action.

After the battle, Tadatsugu recommended to Hideyoshi that Tsuneoki’s second son, Terumasa, succeed Tsuneoki as the next head of the Ikeda clan.  Hideyoshi, however, criticized the failures of the Ikeda family in the battle and refused.  Instead, Hideyoshi proposed promoting Tadatsugu as a direct retainer and a daimyō based at Suwa-Takashima Castle with a fief of 60,000 koku.  Tadatsugu firmly refused the offer and endeavored to defend the actions of the Ikeda, finally convincing Hideyoshi to permit Terumasa to succeed Tsuneoki.  In the sixth month of 1584, Tadatsugu joined in an assault on Takegahana Castle defended by Fuwa Hirotsuna who was allied with the Oda.  In 1585, Tadatsugu became the lord of the castle and received an increase to his fief.

In 1589, Tadatsugu was further granted 5,000 koku in the Haguri District of Mino Province.  This grant came directly from Hideyoshi even though Tadatsugu was a retainer of the Ikeda.  Moreover, these landholdings were deemed free of any levies and without obligatory military service.  At this time, Tadatsugu received a prized haori, or military coat, from Hideyoshi.

After the Conquest of Odawara in 1590, Terumasa was transferred to Yoshida Castle in Mikawa Province and received an increase in his fief to 153,000 koku. Tadatsugu accompanied him, becoming the lord of Tahara Castle with a fief of 15,000 (or 17,000) koku.

For the death in battle of his father and older brother, Terumasa resented Tokugawa Ieyasu.  In an effort to ameliorate him, Ieyasu proposed through the offices of Hideyoshi that his second daughter, Tokuhime, wed him.  Terumasa consulted with Tadatsugu, expressing his intention to reject the offer, but, in the absence of a favorable alternative, in 1594, Terumasa divorced his formal wife, Itohime (the daughter of Nakagawa Kiyohide), and received Tokuhime as his next wife.

After the death of Hideyoshi in the eighth month of 1598, Terumasa leveraged his marriage to Tokuhime to approach Ieyasu.  In 1600, during the Battle of Sekigahara, he joined the Eastern Army led by Ieyasu and participated in the Siege of Gifu Castle.  Tadatsugu served as a deputy for Terumasa and, on 8/22, during the battle at Gifu Castle, issued a letter to the Jōgū Temple.

In 1601, as recognition for his contributions, Terumasa received Himeji Castle and a larger fief totaling 520,000 koku.  As the head of the chief retainers, Tadatsugu was granted a fief of 37,000 koku at Miki Castle in Harima Province.  In 1603, the Igi family regarded themselves as descendants of the Taira-Kamakura clan but were conferred the surname of Tachibana while Tadatsugu was invested with the titles of Junior Fifth Rank (Lower) and Governor of Bungo.  That same year, after Terumasa’s son, Ikeda Tadatsugu, became the lord of Bizen-Okayama Castle, Katagiri Nagamasa served as the shioki karō, or chief retainer in charge of economic and political affairs.  Tadatsugu’s younger brother, Ikeda Tadakatsu, became the lord of Sumoto Castle in Awaji Province while Arao Narifusa served as his shioki karō.

In the eleventh month, Tadatsugu died at the age of sixty-one.  His mortuary tablet is at the Shōnyū Temple in the city of Miki in Hyōgo Prefecture and his grave is at the Honyō Temple.  His eldest son and lineal heir, Igi Tadashige, inherited the headship of the clan.

Character

Despite the fact that Tadatsugu was a retainer of a retainer (the Ikeda) of Hideyoshi, Hideyoshi recognized his abilities.  In the wake of the Battle of Komaki-Nagakute, after Terumasa succeeded his father as the next head of the Ikeda, Hideyoshi ordered the members of the Ikeda family to treat the veteran Tadatsugu in the same manner as Tsuneoki and to be loyal to Terumasa.

After the Battle of Sekigahara, when Terumasa was awarded with a much larger fief, he became obsessively devoted to engaging retainers.  Tadatsugu had misgivings about this owing to the risk that hereditary retainers could forsake the Ikeda family.  Tadatsugu remonstrated hereditary retainers who had shared successes and failures with Terumasa over a long period to focus on their duties and Terumasa also said he would not forget the admonitions.  When close associates of Terumasa’s grandson, Ikeda Mitsumasa, proposed engaging a new military scholar, he rejected the idea, saying that “Our family has our own military strategy,” suggesting that Tadatsugu’s words of admonition carried over to later generations.

Regretful that he could not save Tsuneoki, Tadatsugu rebuilt the temple that had been abandoned below Miki Castle and named it the Shōnyū Temple.  This is associated with the posthumous Buddhist name of Tsuenoki.