So at twelve years of age he had become the 14th head of the Takehara-Kobayakawa clan (竹原小早川氏) and received the name Kobayakawa Takakage (小早川隆景).

He sailed straight toward Miyao Castle in a feint,[6] then retreated so he could be in a position to return the following day, his attack synchronized with the overland assault.

[7] At dawn, Takakage and his 1,500 troops landed before the small fortress, and the sound of shell trumpets signalled that all units were in position and the attack commenced.

As Takakage's force rushed the front gate of Miyao Castle, Mōri and his troops hit the Ōuchi position from behind.

During the following year of 1567 he was dispatched to help the Kôno clan (河野氏) of Iyo Province and at the Battle of Torisaka captured Ozu Castle (大洲城) forcing Utsunomiya Toyotsuna (宇都宮豊綱) to surrender.

When Murakami Michiyasu (村上通康) died that year Takakage sent his widow who was a daughter of Kôno Michinao to marry Shishido Takaie.

[9] In 1556 at May 19, Dōsetsu's forces finally manage to quell the rebellions incited by Akimoto, and he later sent recommendation letters of his subordinates who gave outstanding performance during this operation, such as Korenobu Yufu, Takano Daizen, Adachi Sakyō, and Ando Iesada.

[10] In 1557, the Akizuki clan rebelled due to their collaboration with Mōri Motonari, to which Sorin responded by sending Tachibana Dōsetsu and Usuki Akisumi with 2,000 soldiers to quell their rebellion.

[17] In 1562 of July 13, Dōsetsu and his subordinate Korenobu Yufu,[10] has defeated the Mōri clan army in the battle in Yanagigaura in Buzen Province.

[20] On November 26, there was a battle all day long near Moji Castle, leaving hundreds injured and dead with an unclear result.

[24] However, this truce did not last long as on March 25, Dōsetsu once again fought the Mōri clan army which was led by Koremaki Yufu in The Fourth Battle of Yanagigaura.

[25] In 1569, Dōsetsu was involved in the failed defense of the Siege of Tachibana castle, where the army under Mōri Motonari beat Dosetsu forces with the extensive use of cannons.

[16] Later in the same year, Dōsetsu personally led the Otomo forces against the Mōri clan in Tatara area (located in modern day Higashi-ku, Fukuoka), where they engaged in at least four battles which ended in deadlocks.

[26] In May 18, after several engagements at the Battle of Tatarahama, the Ōtomo army led by Dōsetsu, Usuki Akisumi, and Yoshihiro Akimasa clashed against 40,000 soldiers under Kikkawa Motoharu and Kobayakawa Takakage.

Dōsetsu rode his horse and charged forward unto the enemy camp while drawing his sword.The army of Motoharu and Takakage was unable to resist and was pushed back.

The alliance consisted of Ashikaga Yoshiaki, Mōri Terumoto, Uesugi Kenshin, Takeda Katsuyori and the Ishiyama Hongan-ji monks.

The Ishiyama Hongan-ji was still under siege, and Oda's fleet, commanded once again by Kuki Yoshitaka, made another attempt to break the Mōri supply lines.

However, rather than true ironclads, made primarily or entirely of metal, these craft probably simply had limited iron plating in key locations.

In 1579, Ukita Naoie of Bizen Province believed the fight against Nobunaga was hopeless and claimed illness, only sending a small token force to aid the Mōri.

However, Hashiba Hideyoshi, who also had 30,000 men was faring well and Oda Nobunaga's main army who had just finished defeating the Takeda clan were marching towards the Chūgoku region.

In June of that year Hideyoshi hears about Oda Nobunaga's demise at the Honnō-ji incident by the hands of his former retainer Akechi Mitsuhide and hurries back to Kyoto to get revenge for his master.

Akechi Mitsuhide had sent a secret letter to Mōri Terumoto promising him great things but Hideyoshi's men intercepted the messenger.

This left Takakage with the problem of taking care of the provinces in Kyūshū without help and by the suspicious nature of his death he may have been assassinated by Hideyoshi himself.

Since Saionji Kinmochi (西園寺公広) was also killed at the same time, during Takakage's transportation of men to Kyūshū it seems Hideyoshi was trying to take power away from the Kobayakawa clan by eliminating his best supporters.

He was then relocated in 1593 to Gyeonggi Province where he fought in the Battle of Byeokjegwan with Tachibana Muneshige where they repelled the reinforcement forces of the Ming dynasty.

In 1595 Takakage was appointed to the Council of Five Elders by Hideyoshi along with Ukita Hideie, Maeda Toshiie, Uesugi Kagekatsu, and the famous Tokugawa Ieyasu.

Takakage died two years later at Mihara Castle on July 26, 1597,[2] and was buried at Beisan Temple (Beisan-ji, 米山寺) in Nuta, Numata.