A Samurai-Force conquers a kingdom


By Harald Pöcher


The Japanese prefecture Okinawa lies in the southwest of the Japanese Empire and was once the kingdom of the Ryukyus. Okinawa stands for “Ribbon in the Sea”, and that characterizes the geographic function of this chain of islands between the southern part of Kyushu and Taiwan, as a barrier between the East Chinese Sea and the Western Pacific.


Because of its central geographic position to Japan, Taiwan, China and the Indonesian-Philippine archipelago, the kingdom of the Ryukyus was an important place for trade. At the beginning of the 21st century, Okinawa became a security policy- hotspot in Far East, because the Peoples Republic of China and Taiwan raise a claim on the islands, in particular on the Senkaku Islands and on the Isle of Yonaguni.


The conquer of the kingdom of the Ryukyus by a combined sea and land Operation of a Samurai Force is a shining example of a military operation with far reaching strategic and political consequences. The essay describes the operation and discusses the aftermaths of the Japanese victory until today.


Geography and History of the Ryukyu’s


The name of the Ryukyus is of Chinese origin and it means “glazed horn-dragon”. The Ryukyu Islands number approximately 1.000 islands and spread around a distance of 1.000 km from Southern-Kyushu to Taiwan. The ancient history of the Ryukyus mostly remains in the dark, but archaeological research estimated the islands population back 32.000 years, with a population coming from mainland Japan and Micronesia. In a history book of the 17th century it is reported that a Samurai came from Japan to Okinawa in the 12th century. Today, this story is considered to be an attempt to justify and legalize the demand on the islands by Japan.


The Ryukyus were ruled by kings and tribal chieftains, but it is not the aim of this essay to tell the entire history of the Ryukyus, but for a better understanding it is necessary to explain the cornerstones of history of the Ryukyus since the 14th century. During the 14th and 15th century, the Ryukyu’s were between 1322 and 1429 divided into three kingdoms. At the beginning of the 15th century, the noble Sho-Family of the middle kingdom conquered in 1416 the southern kingdom, and in 1429 the northern kingdom, and therefore became kings of the whole archipelago. The kings of the Ryukyus were officially recognized by the Ming-emperors of China, but for some time the kingdom became tributary.


The new and united kingdom established their capital town in Shuri near the harbour of Naha. The kings of the Ryukyus conquered the most distant islands but they never exercised permanent control on the Senkaku-Islands and of Yonaguni, which belong to Japan today. The Islands of Senkaku and the island of Yonaguni served as important orientation points for the ancient navigation and were therefore well known by China and Taiwan, but the Islands never were occupied by Taiwan and China and remained therefore  as a “Terra Nullius (=no man’s land)”.


The good relationship between the kings of the Ryukyus and the Ming had a great effect on the development of the archipelago. China supported the kings to found a modern administration and to create an efficient economy. The kingdom had its own language, however the most spoken second language was Chinese. After the creation of the united kingdom in 1429, until the 17th century the economy, especially the sea trade, developed admirably, but because of the withdrawal of the Ming from the international trade at the end of the 16th century, the importance of the Ryukyus steadily declined.


At the beginning of the 16th century, nearly 200.000 people lived on the Ryukyus, and today the population of the prefecture of Okinawa is 1.5 million. In Japanese historical books, the Ryukyu’s were mentioned the first time in 1187. The Shimazu, who were the daimyo (=provincial lords) of South Kyushu even raised claim on the islands in 1200. Afterwards, within a period of more than 400 years, it remained only a claim, but around 1590 the king of the Ryukyu was asked by Toyotomi Hideyoshi to join the Japanese occupation force for Korea. The king of the Ryukyus, due to his good relations with China, and knowing that Hideyoshi had far reaching occupation plans which included the occupation of whole China, rejected this demand. After the failure of the invasions of 1592/93, 1597/98 and with Hideyoshis death in 1598, Tokugawa Ieyasu took over the power in Japan after winning the Battle of Sekigahara in 1600 and became Shogun in 1603. After the Battle of Sekigahara, Tokugawa Ieyasu confiscated the land of the defeated landlords. Though the Shimazu fought against the Tokugawa at the Battle of Sekigahara, the Shimazu were not expropriated and the Shimazu were allowed to keep the southern part of Kyushu as their domain. Not later than 1608 the Shogun Tokugawa Hidetada made the Shimazu known that he would welcome a military operation against the Ryukyus conducted by the Shimazu. The Shimazu hoped that an occupation could be successful reached by negotiations, but the king of the Ryukyus rejected the demands of the Shimazu. Therefore the Shogun ordered an invasion of the islands by a Shimazu force.


After the occupation, the kingdom of the Ryukyus came under the influence of the Shimazu and the kings of the Ryukyus became vassals of the Shimazu. At the same time, the shogunate granted every possible freedoms to the kingdom of the Ryukyus, fooling China into believing that the kingdom of the Ryukyu’s are not under the influence of Japan. This situation remained in force for more than 250 years. The situation changed after 1853, when Japan ended its self-determined isolation and began enhancing its territory by occupation of neighbourhood countries. In 1871 Japan attached the Ryukyus and annexed the archipelago as new province Okinawa on March 11, 1879.



The opposing forces

The forces of the kingdom of the Ryukyus


We know very little about the military organization of the kingdom of the Ryukyus. Only from Korean sources do we know that the military was recruited by conscription. Military service was one year, and the military training was supervised by a member of the royal family. The soldiers were organized in groups of hundred, i.e. the royal guard which guarded the royal palace consisted of 100 soldiers,  when the king went on journey, he was accompanied and guarded by 300 soldiers.


Under the rule of the most important king Sho Shin, the military organization was changed:  He introduced the so called “nagiri gun”, which had to fulfil the duty of a modern - and today’s military terminology of a - district army. Furthermore, he gave the order that the units of the army should be organized like the crew of a naval vessel. Every such hiki had a personnel composition enabeling a hiki to solve independently tactical orders. The commander of a hiki was called sedo. The soldiers of a hiki had not only to fulfil military tasks but they also had to work as policemen or as members of administrative staffs. In sum, twelve hiki existed, which were organized into three groups to four ban. The twelve hiki mostly were dislocated as a guard of the royal palace and the inner and outer defence of the harbour of Naha. A ban was named after the sign of the Asiatic zodiac, i.e. ushinohi no ban = ban of the day of the Taurus.  Sho Shin attached great importance to logistics and he had an armory build in Urasoe near the castle of Shuri, in which weapons were stored. The armory was centrally located and could therefore easily be reached by all on Okinawa dislocated troops. Furthermore, he strengthened the fortification around the castle of Shuri, let new castles build on strategic point across the Island of Okinawa and gave the order to build a new street between Naha and Shuri for a better and more rapid deployment of forces. Moreover, he established the position of a boraagumi bugyo, who had to observe innovations of artillery.


The exact personnel strength of the troops at the beginning of the 17th century is not available. From the description of the fightings between the army of the kingdom of the Ryukyus and the Shimazu Samurai army, we know that approx. 1.000 soldiers were deployed to strengthening the garrison of the castle of Shuri and the harbour of Naha was defended by 3.000 soldiers. And on other positions of the kingdom soldiers were also deployed. The soldiers of the kingdom used firearms which were based on Chinese models. Most widely used were so called hiyaa (“fire arms”), triple-barreled shotguns with short barrels which could be used for short distances. Besides such small arms, the soldiers of the king used cannons of a caliber of 7 cm. Most of the soldiers were equipped with lances and swords. The soldiers wore protective equipment which was similar to the equipment that Chinese soldier used in combat. In the popular literature it was mentioned that the defenders of the castle in Shuri used poison snakes against attackers but it is not confirmed in official textbooks of history and official record.



The forces of the Japanese Daimyo

Land Forces


The land forces at the beginning of the 17th century were battle-hardened troops well trained by countless battles during the Sengoku-period (from 1467 until 1600) in which Japan plunged into a series of wars. Under the command of a talented general, a samurai army was usually quite efficient, which can be best illustrated by the examples “five Battles of Kawanakajima (1553-1564)”, “Battle of Nagashino 1575”, “Battle of Sekigahara 1600”, and the “Capture of Osaka castle 1614/15”.


In principle, a Japanese army consists of three types of soldiers. The elite troops were the samurai, the main body were the ashigaru and the Special Forces were the ninja. The samurai were the best trained soldiers of ancient Japan. The word “Samurai” dates back to the Heian period (794-1185) and it means “To serve”. During the Heian period the samurai were the guard of the Emperial court. The advancement of the samurai to its own class of warriors began during the Kamakura shogunate (1185-1333), in which the true supreme power belonged to the Shogun and its military government. The samurai of this period were mounted warriors. The weapons and the equipment of the samurai were of highest quality. The most important weapon of the samurai was his sword, the Katana, which was 60 to 76 cm long. Besides his sword the samurai had two other smaller stabbing weapons, the Wakizashi (45 cm long) and a dagger called Danto. After the introduction of firearms in the middle of the 16th century the samurai made widely use of matchlock rifles.


The production of the body armour of a samurai were artfully and an extensive work. The head and the neck were especially protected by a helmet with a neck protection. And also for the body, the shoulders and the legs the craftsmen created special armour. The food soldier, called ashigaru, was armed with simpler weapons and he was protected with simpler body armour. The Ninja wore special black clothings and in the weapon-arsenal they had special weapons, i.e. close combat weapons, explosives, a sword, tetsu bishi (caltrops) which consisted of sharp iron spikes arranged on the shape of a tetrahedron, shuriken (“ninja throwingstars”), an uchitake, which was a waterproof gunpowder container inside a bamboo tube and kaginawa (Hooked rope) which was the most important climbing device.


After the Battle of Sekigahara in 1600, Tokugawa Ieyasu seized the land of the besieged landlords and divided the country among his allied daimyos. Every daimyo had to maintain his own forces and the daimyo had to provide forces when the shogun needed the troops. The recruitment depended on the prosperity of a domain which was measured in koku; a koku of rice weighted 150 kilograms, and the measurement-unit koku stands for the quantity of rice which was necessary to feed a soldier for a period of one year. For example, a daimyo who owned 200 koku had to recruit 5 soldiers (a mounted samurai, a spear-bearer and three servants). If a daimyo was the owner of 10.000 koku he had to recruit 235 soldiers (20 riflemen, 10 archers, 30 spear-bearer, 10 mounted samurai, 16 samurai as foot-soldiers and 149 servants).


At the beginning of 17th century, the samurai army of the Shimazu was well trained and combat proven. The Shimazu were the daimyo of the old province Satsuma, Oosumi and Hyuga which corresponded largely to today’s prefecture Kagoshima and Miyazaki in the southern part of Kyushu. The Shimazu owned a land which had a value of 402.180 koku. The Shimazu were rich and able to recruit and equip a large army and navy. For the operation, the Shimazu allocated 75.000 koku which corresponded to 1.500 soldiers in personnel strength. A further 320.000 koku and silver were raised by the population.


The Navy


Japan is an island state. The naval forces have been playing an important role since ancient times. The first large naval operation happened in 663 AD when a Japanese fleet sailed to Korea with a large invasion army aboard. The Japanese fleet was severely beaten by a combined Korean-Chinese fleet. The need for warships was particularly high from the 13th century until the beginning of the 17th century, because Japan was threatened by the Mongols, and in the 13th century and at the end of the 16th century, Japan invaded Korea twice.


The Japanese shipbuilder studied Chinese and Korean models and developed their own type of ships. In Japan existed three types of warships: The “atake bune”, the “seki bune” and the “kobaya”. The atake bune was a large warship that was seen as a kind of floating castle, with a closed deck and a superstructure which looked like a Japanese castle. She was powered by oar and sails and had a crew of 80 oarsmen, 60 soldiers with three canons and 30 riflemen. The seki bune was smaller than the atake bune and had no superstructure. The crew consisted of 40 oarsmen, 30 soldiers with one canon and 20 riflemen. The crew was protected by side planks, and the seki bune were actually the backbone of the fleet. The kobaya was a small naval vessel without any protection and it consisted of 20 oarsmen and 10 soldiers and 8 riflemen. Besides these fighting ships,  the ancient Japanese naval forces also used auxiliary vessels, i.e. the “uma fune” to transport horses or the “seiro bune” which was a transport vessel for siege towers. About the sailors life during a sea operation we know little or nothing.


The conditions for living on the ships, especially the sanitary situation, were determined by the tight space aboard, and was the same as on warships of European sea powers of that time. Taking in consideration the proverbial “Japanese discipline” we can conclude that aboard of Japanese warships the living conditions were acceptable. The orderly sequence of the operation without any large frictions is another indication that the living conditions aboard the Japanese warships were adaequate. Furthermore, no epedemics broke out aboard the ships.


The operations plan and the preparation of the operation


The operation plan of the Shimazu provides a surprise attack without a longer siege of the castle of Shuri. At first, the Amami Islands should have been conquered, and afterwards the Japanese attack force had to set up a bridgehead on the island of Okinawa, which should serve as a starting point for the further attack to Naha and the castle of Shuri. The operations plan provided a combined land and sea attack in which the naval forces should attack the harbour of Naha and the land forces should occupy the castles on Okinawa. For the realization of the plan, the weather conditions played an important role, because during certain seasons the islands of Okinawa were heavily affected by typhoons. In this regions only the months April and May have stable weather conditions that would guarantee a secure crossing to the target. Therefore, the starting point of the attack was set at the beginning of April.


The attack force consists of an army command of 119 men, 100 mounted samurai with 200 servants, 700 samurai acting as foot soldiers, 2.100 ashigaru (800 riflemen, 800 spear bearers, 300 archers and 200 otherwise armed soldiers), 2.000 logistic personnel and 3.000 sailors, in sum 8.000 persons. The commander of the attack force was the talented general Kobayawa Gonzaemon Hisataka (1560-1634) and his deputy was Hirata Taroza’emonnojo Masamune.



The course of the invasion and the time afterwards


The invasion army boarded the ships in Yamakawa on the most southern part of Kyushu. In the morning of the 8th of April 1609, the fleet set sail and reached in calm waters the island of Kuchinoerabujima on the evening the same day, where the force set up the camp for the night. On the following day the force reached the islands of Amami, where it had first contact with the enemy in the Kasari bay of the island of Oshima. The attack force was confronted with little resistance and brought the whole islands within for days under control. Afterwards the attack force cleaned the islands thoroughly and destroyed every resistance because they wanted to use the islands as a supply base if Okinawa had to be besieged for an extended time. On its advancement the attack force was involved into a larger fight with the enemy on Tokunoshima, which ended with a victory of the attackers. The defenders lost nearly 300 soldiers. On 24th of April 1609, the attack force was able to continue its attack and it landed on the 28th of April on the island of Okinoerabujima, which was conquered after a short skirmish. Because the attack force was three weeks in action the commander decided to take a sufficient rest break. Afterwards the attack force should land on the Bay of Unten in the northern part of Okinawa, bypassing the small island of Yoronto.


The island of Okinawa is a long-streched island with a north-south extension of 115 km. The king of the Ryukyus deployed most of his troops on Okinawa. The most important administrative, economic and military installations were located on the southern part of Okinawa near the harbour of Naha and the castle of Shuri. The castle of Nakijin, which dominated the Bay of Unten, was located in the north of Okinawa.  


Although the Bay of Unten was dominated by the castle of Nakijin, the commander of the attack force decided to land his forces in the bay to obtain a favourable position for the further attack to the island’s south.  To avoid that his attack force would come within the effective range of the weapons of the castle of Nakijin, the commander decided that the forces should not land at the bay directly, but on Kourijima, an island off the coast. The defenders didn’t attempt to attack the landing force because they hadn’t enough troops available, but now the castle was falling in the hands of the attacker, but the defenders nearly lost 500 soldiers. After the fall of the castle, the attacking force was able to use the harbour of Unten without any risk. The attack force didn’t stay long at the secure anchorage and sailed along the west coast to another anchorage near Yomitan. After landing on the 3d of May, the attack force was divided. The bulk of the naval forces had the order to sail along the coast to Naha to conquer the harbour. The second force, with the landing force, got the order to attack and occupy the castle of Shuri. After the two operations, both contingents should then unite at Naha. The king of Okinawa was fully aware of the crisis and sent 1.000 soldiers under the command of Nogo Ryoho to the north. Over the last days in April and the first days in May, heavy fightings over the castle took place. On its advance to Urasoe, the land forces took the important bridge near Tairabashi. This success meant that the way to the castle of Shuri was open. The naval forces had less luck when occupying the harbour, because the entrance of the harbour was controlled by the two fortresses Mie and Yarazamori and a chain which was in place between the both fortresses. The Japanese naval forces were prevented to invade the harbour by these defence preparations and had to withdraw. The commander therefore decided to land near Makiminato north of the harbor and to occupy the harbour by a land attack. Near Urasoe, both marching columns united and attacked the castle of Shuri. The castle of Shuri fell into the hands of the attacking force on 6 of May, and the king and his family were captured. Afterwards, the attack force occupied the harbour and began plundering. After the victory - as it was then the habit – the victorious force celebrated for three days by drinking a lot of Sake and eating plentifully.


After the operation, the commander left a strong guard at Okinawa, and sailed with the prisoners back to Japan, where he has triumphantly welcomed on the 28th of May. The captured king was brought to Tokugawa Ieyasu and to the Shogun Tokugawa Hitetada. After swearing oaths and adopting the statues of a vassal, the king was allowed to go back to Okinawa in 1611.


Evaluation of the operation from a strategic, operational and tactical view


The success of the operation of a Samurai force against the kingdom of the Ryukyu’s was analyzed more than once. All the experts came to the result that the success was mainly based on an exact planning, the choice of the right weapon systems and a perfect coordination of fire and maneuver by the attacking forces .


The analysts came to the conclusion that, due to the low personnel strength of the attack force, it would have been better for the defenders to pursue a strategy of attrition, with ambushes and raids, instead of concentrating all the troops near the castle of Shuri and the harbour. Furthermore, they critized the lack of use of fire arms by the defenders.


The strategic value of the victory of 1609 came into full effect in the 19th century, when Japan annexed the Ryukyus and became owner of the island chain according the international law. Therefore, in the current conflict about the ownership of Senkaku Island, the Japanese government can argued that it is the owner of the islands accordingly to international law and by normative force.