In this post I will explain why Satsuma won the Invasion of Ryūkyū in 1609, and how Ryūkyū could’ve stopped it.
In the early 1590s, Japan invaded Korea, and Satsuma’s samurai were the spearhead. They marched through the countryside, setting everything on fire to cause confusion, killing soldiers and civillians alike, and when they came upon the walled cities of Korea, they swept the walls with volleys of gunfire, scaled the walls with ladders, and busted through the gates with heavy axes and hammers. They fought like this for almost a decade, and they would use this same tactic on Okinawa to great effect.
Ryūkyū was an early adopter of firearms, its soldiers often armed with three-barreled “hand cannons”, and having some of the best artillery in East Asia. However, by 1609, Satsuma had acquired European muskets, which were far more superior to the hand cannons still used by Ryūkyū.
In addition, the design of Ryūkyūan gusuku also gave advantages to Satsuma’s tactics. Gusuku walls are relatively low, and the parapets are also low. In order to fire on the enemy from the wall, one had to expose themself. There were gunports near the gates, but the gatehouses were often made of wood.
Lastly, Satsuma split its forces in half to make a two-pronged attack, one by sea and one by land. This split was decisive in the capture of Shuri Castle.
As for Ryūkyū’s shortcomings, there were many, but the most glaring of which being, for a nation famed for wide-spread maritime trade used to fighting off pirates, there was zero response from Ryūkyū’s navy. Intercepting Satsuma’s fleet before they reached Okinawa, or even Amami Ōshima, would’ve been a game changer. Satsuma had 3,000 men in a fleet of 100 ships. Ryūkyū’s navy had 70–100 ships. Had there been a naval battle, given the prowess of Ryūkyūan sailors, Satsuma’s army would’ve been crippled and would certainly struggled to capture even the Amami Islands.
The second major failure was the response from the Ryūkyūan army after Satsuma landed on Okinawa. When the Satsuma fleet came to Unten Harbor in Northern Okinawa, the troops in nearby Nakijin Castle did nothing. Satsuma attacked and captured the castle. An army of reportedly 1,000 marched north to assist the defenders at Nakijin, but reportedly half the army was lost. After that, Satsuma landed an army in Yomitan, near where the Americans would land 336 years later, and very near Zakimi Castle. Three more major gusuku were between the samurai and Shuri Castle: Katsuren, Nakagusuku, and Urasoe. Again, the defenders stayed in their positions and let the samurai pass. Satsuma attacked and captured Urasoe Castle before moving on Shuri. Had the Ryūkyūan soldiers stationed at the other gusuku actually attempted to attack Satuma’s forces, the samurai would’ve been stopped and possibly surrounded.
The last major failure was actually in part due to Ryūkyū’s only success: the defense of Naha from the naval attack. While Satsuma’s army marched overland towards Shuri, their fleet attemped to capture Naha via Naha Port. On either side of the entrance to the harbor stood a gusuku with an iron boom chain between them. Each gusuku had heavy artillery which blasted Satsuma’s ships. Most of Ryūkyū’s soldiers in the Naha-Shuri area moved to defend the harbor, but this left Shuri Castle’s defense weak and open to attack. Reportedly 3,000 troops had assembled to defend Naha from the naval attack. Had such a large force been present at Shuri Castle, the samurai wouldn’t have even gotten close with only half their army. The only reason why Satsuma won even when they were outnumbered is because they captured King Shō Nei. Had the King retreated to a gusuku further south or even to the southern islands of Miyako or Ishigaki, Satsuma’s army would’ve been crushed even after taking Shuri Castle. This is the senario that played out in Korea almost two decades earlier.
In conclusion, I would say that Ryūkyū lost the war due purely to strategic incompetence. It is a shame and wonder that such a small force could conquer a whole kingdom in a couple of months. But I will repeat: Ryūkyū could’ve won. It was far from the meek, defenseless and peace-loving country that many people believe it was. In fact, Ryūkyūan peichin had defeated Satsuma samurai numerous times while Ryūkyū expanded north, as far as Gajajima, just 80 miles from Satsuma’s homeland.
My next post will be about the American bases in Okinawa today.