Chōshū Domain The was a feudal domain of Japan during the Edo period ( 1603 – 1867 ) . It occupied the whole of modern day Yamaguchi Prefecture . The capital city was Hagi . It was coterminous with Nagato Province : in fact , " Chōshū " was simply shorthand for the province . The domain played a major role in the Late Tokugawa shogunate . It is also known as the . History . The rulers of Chōshū Han were the descendants of the great Sengoku warlord Mōri Motonari . Mōri Motonari was able to extend his power over all of the Chūgoku region of Japan and occupied a territory worth 1 , 200 , 000 koku . After he died , his grandson and heir Mōri Terumoto became daimyo and implemented a strategy of alliance with Toyotomi Hideyoshi . This would later prove to be a great mistake . After Hideyoshi ' s death , the daimyo Tokugawa Ieyasu challenged the Toyotomi power and battled with Hideyoshi ' s trusted advisor Ishida Mitsunari at the Battle of Sekigahara . Mōri Terumoto was the most powerful ally of the Toyotomi and was elected by a council of Toyotomi royalists to be the titulary head of the Toyotomi force . However the Toyotomi forces lost the battle due to several factors tied to Mōri Terumoto : Despite its inactivity , the Mōri clan was removed from its ancestral home in Aki to Nagato Province ( also known as Chōshū ) , and its holdings were drastically reduced from 1 , 200 , 000 to 369 , 000 koku . This was seen as a great act of betrayal to the Mōri clan , and Chōshū han later became a hotbed of anti - Tokugawa activities . The origins of this were evident in the tradition of the clan ' s New Year ' s meeting . Every year during the meeting , the elders and the administrators would ask the daimyo whether the time to overthrow the shogunate has come , to which the daimyo would reply : " Not yet , the shogunate is still too powerful . " This dream would eventually be realized some 260 years later , when the domain joined forces with the Satsuma Domain and sympathetic court nobles to overthrow the Tokugawa shogunate . They also led the fight against the armies of the former shogun , which included the Ouetsu Reppan Domei , Aizu , and the Ezo Republic , during the Boshin War . The domains ' military forces of 1867 through 1869 also formed the foundation for the Imperial Japanese Army . Thanks to this alliance , Chōshū and Satsuma natives enjoyed political and societal prominence well into the Meiji and even Taishō periods . Economics . The initial reducing of 1 . 2 million to 369 , 000 koku resulted in a large shortfall in terms of military upkeep and infrastructure maintenance . In order to bring the domain ' s finance out of debt , strict policies were enforced on the retainers : Previously , as a result of high taxation , farmers secretly developed farms far inside the mountains as a private food source . A new land survey was conducted within the domain in which many hidden farms were discovered and taxed . The domain also began a strict policy with regard to trade . Laws were also passed in which the profitable trade of the " four white " s were controlled by the domain : paper , rice , salt and wax . Some of the profits , and a large amount of the tax revenues from this trade , went into the domain coffers . These policies greatly strengthened the domain ' s finances and allowed the daimyo more effective control over his territory . However , these policies angered peasants and displaced samurai alike , resulting in frequent revolts . Politics . The capital of the domain was the castle town of Hagi , which was the source of Chōshū ' s alternate name of Hagi han ( 萩藩 ) . The domain remained under the rule of the Mōri family for the duration of the Edo period . Because the shogunate frequently confiscated domains whose daimyo were unable to produce heirs , the Mōri daimyo created four subordinate han ruled by branches of the family : During the Edo period , the main branch died out twice and heirs were adopted from both the Chōfu branch and the Kiyosue branch . The Mōri daimyo , as with many of his counterparts throughout Japan , was assisted in the government of his domain by a group of karō , or domain elders . There were two kinds of karō in Chōshū : hereditary karō ( whose families retained the rank in perpetuity ) and the " lifetime karō , " whose rank was granted to an individual but could not be inherited by his son . The hereditary karō were either members of minor branches of the Mōri family , or members of related families such as the Shishido and the Fukuhara , or descendants of Mōri Motonari ' s most trusted generals and advisors such as the Mazuda , the Kuchiba and the Kunishi . The lifetime karō were middle or lower samurai who displayed great talent in economics or politics and was promoted to karō by the daimyo . One such person was the great reformer Murata Seifu .