After the Sengoku Jidai - the all-out war between the Japanese clans - came to the end,

it became clear to the winners that Japan would need to find another target for the

hundreds of thousands of warriors now roving around the shattered country. Toyotomi Hideyoshi

united the country for the first time in over a century. Now that he could harness some

of the most veteran armies in Japanese history, he would launch a devastating invasion of

Korea. Welcome to the new Kings and Generals series on the Imjin War, which our patrons

and youtube members selected to be covered next.

________________________________________ Toyotomi Hideyoshi’s dream to unite Japan

into one nation was almost a reality. He had claimed Honshu in its entirety after succeeding

his betrayed master - Oda Nobunaga - in 1582. Shikoku was subdued in 1585, and Kyushu fell

soon after in 1587. However, like Nobunaga before him, Hideyoshi believed that his power

ought to extend beyond the confines of his small island nation, and was convinced his

destiny was to conquer further afield.

The rival daimyo who swore to follow Hideyoshi were allowed to keep their demesnes and were

promised more lands and spoils as the Land of the Rising Sun came ever closer to unification.

This was precisely the problem, as with no more battles to fight or gains to be had,

they would surely begin to plot and scheme against Hideyoshi. Aware of this fact, he

began to make his plans in the late 1580s, hungrily eying Korea as the initial target,

and the Chinese Ming Empire after that.

The great unifier’s most recent conquest was the island of Tsushima, located at the

midpoint of the Tsushima Strait. The lords of this clan - the Sō - now became Hideyoshi’s

vassals, and were ordered to deliver a message to the Koreans. It was a threat of invasion

that put the Sō in a difficult spot. Sō’s long relations with the Korean Joseon monarchy

made them ideal diplomats, but the outbreak of hostilities would damage the trade which

granted the clan much of its wealth.

Aiming to soften the diplomatic blow as much as he could, Sō Yoshishige altered Hideyoshi’s

message to the Korean court. It now demanded that a simple tribute mission be sent to Japan

in order to confirm Korea’s respect. In a lethal blunder, the Sō clan leader sent

a rough, hardened subordinate known as Yutani Yasuhiro to deliver the message, instead of

going himself. Yasuhiro offended his Korean hosts by insulting the size of their spears

compared to the Japanese and mocking their lifestyle. Not content with that, the brash

envoy warned: “Your country will not last long! Having already lost the sense of order

and discipline, how can you expect to survive?”.

The uncouth nature of the envoy’s conduct, in addition to the unacceptable terms of Hideyoshi’s

edited letter, led to the Koreans’ refusal. Naturally, Hideyoshi was furious at the failure

and ordered that Yasuhiro and his entire family be killed. Sō Yoshishige was punished less

severely, being deposed as daimyo of Tsushima by his adopted son Yoshitoshi, who Hideyoshi

considered more trustworthy.

Over the next few years, more embassies were sent from Japan to Korea and vice versa. In

a crucial visit to Kyoto during 1590, Korean courtiers failed to gather intelligence on

just how powerful Hideyoshi’s military was, leading their government to underestimate

the imminent danger. Furthermore, the issue divided the Korean court factions, named for

the location of their respective headquarters in Seoul. Members of the ‘Westerner’ faction

gradually came to realise the very real peril Japan posed, but any attempt to prepare for

the invasion was actively opposed by the ‘Easterner’ group.

In Japan, a colossal war machine was gearing up in the summer of 1591, beginning with Hideyoshi’s

establishment of a massively fortified headquarters complex on the island of Kyushu. From there,

he oversaw the levying of a massive army comprising 335,000 total troops, 158,000 of which would

cross to Korea itself. The levies were raised by the individual daimyo, who were obliged

to supply a predetermined number of men according to the size and wealth of their fiefdom in

a system known as gun’yaku. However, it is notable that other political factors could

influence a daimyo’s required contribution, such as their standing with Hideyoshi.

The 158,000 strong invasion force consisted of 82,200 men from Kyushu, which was closest

to Korea, 57,000 from Honshu, and 19,600 from Shikoku. How this giant force was equipped

must be discussed for a moment, as it is often common to envision Japanese armies as something

different to reality. Rather than an army of samurai wielding katanas, the majority

of Hideyoshi’s invading troops were instead the humble ashigaru, peasant foot soldiers

armed with swords, spears and bows . As the high-tech spearhead, Hideyoshi used a considerable

number of lightweight arquebuses, but the exact number of troops who possessed one is

not known, perhaps one third. The plan itself was to be a domino rolling through Asia. When

the Koreans were conquered, they were to supply manpower and material for the push into China.

When the area around Beijing was conquered, that area would supply manpower for a push

further into the Middle Kingdom, and so on.

The invading force would be ferried to Korea by 700 assorted ships which, along with their

crews, were requisitioned from the various daimyo of the coastal provinces. These were

mostly repurposed merchant or civilian vessels. Though Hideyoshi had a massive army at his

disposal, in addition to high-quality military technology on land, naval power would prove

a problem for him throughout the coming conflict. The Koreans had just two advantages over the

Japanese: their superior shipbuilding and cannon technology. In addition to their relative

lack of knowledge of European-style firearms that the enemy possessed, corruption in Korea

was rampant, leaving military units neglected, untrained and lazy. The kingdom was not ready

for the storm that was coming, but one appointment was made which would prove decisive.

A forty-six-year-old career soldier Yi Sun-shin was promoted to command the navy of Cholla

province. After being assigned to Cholla in late 1590, Yi immediately understood that

his province could serve as a possible invasion route. Determined to be as prepared as he

could, he spent a year diligently studying naval command, whipping his men into shape,

and repairing infrastructure.

After being delayed multiple times, three contingents of the first wave were ready to

sail by May 22nd. On the 23rd, 18,700 troops under the command of Konishi Yukinaga and

Sō Yoshitoshi set out for Busan. The warships earmarked to guard the troop transports had

not arrived, and so this fleet was completely vulnerable.

Though initially believing the ships on the horizon were part of an abnormally large trade

mission, the Korean commanders in the Busan region gradually came to realise that the

invasion had begun. They could have used the superior warships under their command to assault

the undefended Japanese fleet, but they failed to do so. By nightfall on May 23rd, around

400 transports crowded the waters off Busan. The fleet rested that night in the harbour,

completely unopposed. After a final demand for an unopposed Japanese crossing to China

was rejected, the landings began.

At 4am on May 24th 1592, 5,000 men under Yoshitoshi disembarked onto the land, followed by another

7,000 under Yukinaga. Eventually, the entire first contingent was on land and a Japanese

army had landed on Korean soil without a single shot being fired. After two brief sieges,

the main fortresses at Busan and its harbour fell, triggering panic among military leaders

in surrounding provinces. Instead of acting decisively, incompetent Korean naval commanders

scuttled their sizeable provincial fleets and destroyed their weaponry and provisions,

retreating north as quickly as they could.

With Busan secured, proud Yukinaga would not wait for reinforcements as instructed. Instead,

he immediately pushed north along the middle of the peninsula on May 26th, marching at

a blistering pace. This daimyo either wished to monopolise the glory of seizing the capital

for himself, or may have been anxious to break out of his beachhead before the counterattack.

This invading force first came to the deserted town of Yangsan, then went onto Miryang and

Daegu on May 28th, conquering and plundering as they did. Realising he had to mount some

opposition, the governor of Gyeongsang province - Kim Su - tried to lead a force south to

meet the Japanese. However, he soon withdrew without fighting after learning that Dongnae

had also fallen.

News of the Japanese invasion had reached Yi Sun-shin in Cholla on May 25th, along with

the shocking knowledge that both of the Gyeongsang navies had already self-destructed. However,

Yi waited patiently; he had orders to defend his segment of coastline and would do so.

He remained confident that the Japanese could be defeated on the seas despite their superiority

on land, so Yi was biding his time.

Meanwhile, the second Japanese army landed in Busan on May 28th under the command of

Kato Kiyomasa. The troop ships this time disgorged a fearsome contingent of 22,800 soldiers.

Realising that the vanguard under Yukinaga had not waited for him, the irritated Kiyomasa

also swiftly pushed forward. He took the eastern route, seizing the cities of Ulsan, Kyongju,

Yongchon, Sinnyong, and Kumo on the path to Seoul. It would not be his rival Yukinaga,

but he, who reached the capital first.

To the south, Hideyoshi’s third contingent under Kuroda Nagamasa arrived at Angolpo on

the 29th. This force consisted of 11,000 troops who would take the western route north, after

seizing the nearby fort at Kimhae. Three Japanese armies were now set to converge on the Korean

capital at Seoul, but they would not get to the city totally unopposed.

Revered Joseon general Sin Rip had assembled a sizeable resistance army of 8,000 at Chungju

- around 100 kilometres south of the capital - and he intended to fight. The ragtag agglomeration

of cavalry troops, officers who had retreated from the south, and hastily raised levies

from the north, possibly could have held the Choryong pass - General Sin’s original plan.

However, retreating Korean units revealed that it had already been lost, and instead

Sin chose to do battle at Chungju on an open field.

At midday on June 6th 1592, as the Japanese were descending from the Choryong heights,

General Sin drew up his army outside Chungju on a stretch of flat ground, hemmed in by

a hill called Tangumdae to their flank and the South Han river behind them. This was

a death trap with no possibility of retreat, and this was precisely the point. Placing

troops in this kind of situation was a long-established Chinese military tactic which had led to remarkable

victories in the past. Perhaps the Koreans could use it to halt ‘the robbers’, as

they derisively called the Japanese.

As Yukinaga’s first contingent descended from the heights, Kiyomasa emerged from the

eastern route and managed to catch up with his rival daimyo near Chungju. The latter

was angered that Yukinaga had stolen the glories by storming ahead and demanded to now take

the lead with his own force. He refused, and Kiyomasa decided that he would take revenge

on his rival at Chungju. As Yukinaga began his advance towards the city from the southeast,

the second contingent stayed behind, hoping their rivals would be defeated.

The attacking troops fanned out as they approached the town, finally emerging opposite General

Sin’s force in a vast arc. At 2PM in the afternoon of June 6th, Yukinaga divided his

army into three main units. 10,000 soldiers under himself and his retainer Matsuura Shigenobu

formed the vanguard, while Sō Yoshitoshi and his 5,000 strong contingent formed the

left flank. Finally, 3,700 assorted troops commanded by their minor daimyos - Arima Haru,

Omura Yoshiaki, and Goto Sumiharu, were placed on the right. Arquebusiers were placed on

the front lines of the Japanese army, while behind them stood ashigaru footmen armed with

melee weapons.

When arrayed in battle formation, the Japanese advanced with a roar of musket fire. It was

hardly even a contest; General Sin’s amateur forces were almost immediately overwhelmed

by flying arquebus balls and began to suffer devastating losses. The peasant soldiers began

to rout under the pressure, but the brave General would not retreat so easily. He led

his crack cavalry in a headlong charge towards the enemy line. It was to no avail. The arquebusiers

rained withering musket fire down on his horsemen, breaking the charge before any contact was

made. In short order, General Sin’s 8,000 strong army had ceased to exist, many survivors

of the initial slaughter being hunted down by pursuing ashigaru soon after. Sin threw

himself into a natural spring adorned in full armour, committing suicide by drowning.

Japanese armies had advanced hundreds of miles into Korean territory in under a month, allies

seemed nowhere in sight, and the only significant defensive army had been crushed. It looked

as though the Joseon kingdom was finished, but the war was just starting, and in the

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