Chapter 106: Asiatic Northern War Part V - Every Island On the Table
The Battle of Umashima cemented a stalemate on the seas, with Japan unsuccessful at breaking Joseon’s stranglehold over the Tsushima straits or the amphibious besieging of Tsushima Island itself. Nor could Byeon Ge-up seize control of the Kanmon straits and its increasingly fortified and garrisoned shores on both sides. The Joseonite admiral therefore turned his attention towards taking the Okishima and Iki islands and harassing the coasts of Kyushu. Sengoku Masatoshi and Matsura Shigenobu, whose domains encompassed Oki and Iki Islands respectively, had been expecting such a move to come ever since war broke out in the seas. As such, they had been preemptively bolstering the islands’ defenses, stocking up on provisions, and taking in reinforcements from the home islands.
An attack upon Iki island came first on July 20th in conjunction with Byeon Ge-up’s strategy of harassing coastal Kyushu. While the main navy quickly surrounded the island, smaller ships attacked any Japanese ships they came across and unleashed cannonfire upon various coastal batteries and fishing villages. The Joseon navy quickly faced a formidable response that ended any chance of taking the island, however. Firstly, Iki was close enough to Kyushu proper where Joseon ships could be bombarded from the coast, and this disrupted Joseon’s encirclement of the island. Secondly, Tagawa Seikou and the main navy had finally arrived, reinforced by ships from the various Kyushu daimyo. They swiftly rebuffed the smaller ships raiding the coasts and headed north to break the encirclement. Alerted of Seikou’s approach, Byeon Ge-up weighed the possibility of abandoning the assault and reforming for the open seas to directly confront the Japanese navy. Due to the complicated nature of such a maneuver in a rather short amount of time, he decided against going down that path and instead retreated in good order from Iki, ending the assault after only 6 days. The island had been saved.
Portrait of Matsura Shigenobu
After driving Byeon Ge-up out of the area, Tagawa Seikou set his eyes on liberating Tsushima, where Sou Yoshizane continued his resistance against the Joseon fleet albeit with less men and less supplies every passing day. By the middle of the summer, Japanese control of the island had been reduced to Kaneishi Castle and its immediate surroundings. When more ships from the former assault force against Iki began joining the enemy fleet, things looked bleaker than ever and Yoshizane even began writing his final will and preparing for his seemingly inevitable seppuku. On August 14th, however, a Shimazu vanguard of ships commanded by Hongou Hisamoto (北郷久元) reached Tsushima and exchanged fire with the Joseon fleet, attempting to break the encirclement. Caught by surprise, Gim Jeong-il lost a few ships against his Shimazu foe before Hisamoto’s fleet snuck away. A few days later, the Japanese returned, this time directly overseen by Seikou and accompanied by more ships. This time, the Japanese broke the encirclement, forcing Jeong-il’s fleet to retreat and relieving Tsushima of its months-long besieging.
Okishima wouldn’t be so lucky. A smaller fleet had begun a preliminary assault upon the island on July 23rd, and they would also be reinforced by many of the ships from the Iki invasion force. Sengoku Masatoshi had only 1,000 men and lacked less provisions and defenses than the larger Tsushima. Most of the province quickly fell outside of Oki Castle (隠岐城) [1] and on August 7th, the Joseon fleet successfully broke through the defenses of the fortified stronghold. Masatoshi would commit seppuku and although scattered resistance continued into the fall, Okishima was now under Joseonite control. The neighboring islands of Nishinoshima (西ノ島), Chiburijima (知夫里島), and Nakanoshima (中ノ島) also fell in the aftermath of the fall of Okishima. The capture of Oki province was humiliating for Japan as for the first time in nearly 4 centuries, a foreign power had successfully invaded the home islands. Worse, Seikou could not immediately respond and attempt to capture the islands, for Byeon Ge-up still commanded a formidable navy that now wrestled with the Japanese navy over control of the Tsushima Straits. The task of retaking the islands would be left to Nanbu Naofusa, who was still preoccupied with transporting the rest of Kaga Nagaaki’s army to the mainland and remaining on guard to prevent Joseon from either disrupting that task or holding dominion over the more northerly waters.
These developments on the seas continued to exacerbate growing economic concerns and disruptions of trade as the war made the seas more dangerous traversing for anyone, including foreign and native merchants. This was especially the case in Sakai and Shimonoseki, who heavily relied on the Kanmon Straits and saw all of its trade impacted. Economic anxiety quickly transitioned into outright xenophobia towards resident Joseonites, and the latter became scapegoated and frequently experienced public mockery and discrimination. The xenophobia reached new heights after the capture of Oki province and would lead to horrific events. In September, the local magistrates of both cities succumbed to paranoia and ordered the arrest and detainment of prominent Joseonite merchants suspected of being spies for the Joseon government. News of this quickly spread among the populace, and a handful decided to take matters into their own hands. On the night of October 1st, the Anti-Joseon Riot of Shimonoseki (下関反朝鮮一揆) took place, where a large angry mob gathered and decided to take matters into their own hands, breaking into and plundering the Joseon quarter of the city. Several women were raped while many men were dragged out of the homes and beaten or even lynched in some cases. It was a few hours before the magistrate’s men arrived on the scene and ended the bloody carnage, but it was too late and the riot had claimed 24 casualties and dozens more injured. Smaller incidents took place in Sakai but were quickly suppressed by the local magistrate there. Nevertheless, damage had been done and diplomatic relations between the two warring nations plummeted and the Shimonoseki riot triggered a mass exodus of Joseonite merchants and resident artisans took place throughout the entire realm.
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As economic anxiety and xenophobia gripped urban centers on the home islands, the war on the sea continued. The Japanese now laid their eyes on Jeju Island as they hoped to oust Joseon entirely from its own islands. The main obstacle to this lofty goal was of course Byeon Ge-up and his formidable armada, and Tagawa Seikou knew that a direct clash with his Joseonite rival was inevitable. Despite this looming threat, he set off for Jeju Island with his main fleet, seemingly preparing for an amphibious invasion of the island. Naturally, Joseon’s chief admiral set off to intercept the Japanese before they could reach Jeju. What Byeon Ge-up didn’t know was that he had fallen directly into a trap, for Seikou had anticipated such a move and had ordered Hongou Hisamoto to lead a smaller fleet from Kyushu towards the Geomundo archipelago. In fact, Seikou had no intention of committing to an invasion of Jeju at that point and was seeking to draw the Joseon fleet into open waters to be eviscerated. His plan came to fruition on November 6th, 1667 just off the island of Daesambudo, a part of the Geomundo archipelago. The Joseon fleet headed straight towards Tagawa Seikou’s fleet numbered 49 ships while the latter was made up of 34 ships, with Hisamoto’s contingent made up of 22 ships. Seikou was accompanied by many of his personal junks and he positioned himself in his personal ship, the Zheng, which was the largest and most formidable warship in the Japanese navy.
Pre-battle formation (blue = Joseon, salmon = Japan)
The battle began with the 3 contingents of the Joseon navy boxing in the Japanese from the north and west. Supporting Byeon Ge-up on the western wing of the Joseon navy was Gim Jeong-il who sought to recover from the humiliating end of the besieging of Tsushima. Per Joseon tactics, the panokseon ships were concentrated on the frontlines, supported by galleons and other heavy warships, while more modest ships formed the middle and reserve ranks. Tagawa Seikou deployed the heavy portion of galleons northwards and despite their numerical inferiority, their firepower gave him the edge on the northern front. The Japanese navy faced more difficulties from the northwest and west but Seikou’s experience and shrewdness more than matched that of Byeon Ge-up’s. Nevertheless, Seikou knew that unless Hisamoto’s fleet arrived on time, he would probably lose. Luckily, his deputy arrived with his fleet a few hours into the naval battle, sweeping behind the western wing of the Joseon navy. By the time Jeong-il saw them, Hisamoto’s ships had begun firing upon his own contingent, and Jeong-il’s wing would crumble before the relentless cannonfire coming from both sides. Gim Jeong-il himself would drown in the ocean along with many of his ships and sailors. Meanwhile, the rest of the Joseon navy started experiencing heavier losses and it wasn’t long before Byeon Ge-up ordered a retreat back to Busan. In the end, Joseon had lost 17 ships while Seikou had lost just 5, marking the Battle of Daesambudo as a decisive Japanese victory.
Latter half of the battle
Seikou’s true intent soon revealed themselves when he declined to follow up on the victory and assault Jeju Island, his ships sailing back to Shimonoseki and Nagasaki to wait out the winter. That task would be saved for the following year. This further embarrassed Byeon Ge-up, and he was subsequently removed from his post and replaced by Yi Sang-seon. The new chief admiral of the Joseon navy was faced with a completely new state of affairs in the seas. Now, Joseon was largely on the defensive, its gains completely reversed outside of Oki province. He would spend the winter constructing new ships, mobilizing new sailors, and repairing the damages wrought by the Japanese in recent months. When the new year dawned, the naval war would inevitably intensify once again.
[1]: Built in 1611 ITTL.