Notable actions of Zhejiang troops during the Imjin War

When I was writing about infantry formations of the Imjin War, I got curious: did these two military formations ever meet in Korea? This leads me down to a rabbit hole to seek out notable Zhejiang troops' exploits during Imjin War. As it turns out, yes, Zhejiang troops did come head to head with the Japanese a few times, and below is a non exhaustive list of notable Zhejiang troops actions, arranged in chronological order.

1) Siege of Pyongyang

1.1) Assault on Matsuyama Castle (松山城) on Mount Morangbong (모란봉 or 牡丹峰)

Date: February 9, 1593

Commander: Zhejiang commander Wu Wei Zhong (吳惟忠), Northern commander Cha Da Shou (查大受), Korean warrior monk commander Yujeong (유정 or 惟政)

Strength: 3,000 Zhejiang infantry, 500 Ming cavalry, 1,500 Korean warrior monks.

Summary: The combined force suffered heavy casualties and failed to capture Matsuyama Castle. Wu Wei Zhong was shot in his chest but continued fighting, and he was later commended for his valour.

Context: Matsuyama Castle was built on Mount Moranbong, a hill located just outside the northernmost part of Pyongyang city wall, and served as a high vantage point overseeing Japanese defence within the city. While Wu Wei Zhong did not capture the castle, his action tied down Japanese troops inside the castle, preventing them from sallying out to flank the main Ming contingents attacking Potong Gate (보통문 or 普通門) and Chilsong Gate (칠성문 or 七星門).

1.2) Assault on Hangu Gate (함구문 or 含毬門), southern gate of Pyongyang City

Date: February 9, 1593

Commander: Zhejiang commander Luo Shang Zhi (駱尚志), demoted Northern commander Zu Cheng Xun (祖承訓), Northern commander Li Nong (李寧), Joseon commander Kim Ung-seo (김응서 or 金應瑞), Joseon commander Yi Il (이일 or 李鎰)

Strength: 600 Ji Garrison Southern infantry, 700 Ming cavalry, unknown number of Joseon troops.

Summary: Ming troops disguised themselves as Joseon troops to deceive Japanese defenders on the wall. The Japanese, who thought lowly of the combat prowess of Koreans, thus focused their defence elsewhere. This allowed Luo Shang Zhi and his Southern infantry to storm and capture the city gate by surprise. Zu Cheng Xun then led the Ming cavalry into the city and shot the rest of the Japanese defenders to pieces with three-barreled matchlock guns.

Note: Since most Joseon troops were following Wu Wei Zhong and Luo Shang Zhi and witnessed their actions first-hand, the effect of their exploits was greatly exaggerated in many Korean sources. Luo Shang Zhi was sometimes portrayed as the first to capture a Pyongyang's city gate and the main contributor to Ming victory, while in reality his contingent was more of a diversionary force. The majority of battles were actually fought at Potong Gate and Chilsong Gate at the northern part of the city. Unfortunately, there were no Koreans there so these were largely neglected.

2) Battle of Angang

Date: November 25, 1593

Commander: Wu Wei Zhong, Lu Cheng En (陸承恩)

Strength: 1,000+ Zhejiang infantry, some other Ming and Joseon infantry

Summary: Ming army was lured into tall grass and ambushed by large numbers of Japanese troops, suffering over 300 casualties. Japanese troops began to look down on Ming infantry afterwards.

Context: This battle happened while the peace talk between Ming Dynasty and Japan was underway, and most of the Ming army already pulled out of Korea. Katō Kiyomasa (加藤清正), who was dissatisfied from being left out of the negotiation. decided to sabotage it to spite his rival Konishi Yukinaga (小西行長). Citing safety concern of Japanese envoy Naitō Joan (内藤如安) as an excuse, he launched an incursion into southern Gyeongju Province in October 1593, although the initial attempt was blocked by Wu Wei Zhong and Luo Shang Zhi. Not one to give up easily, Katō Kiyomasa made another attempt by splitting his army into three contingents and launched an attack on Angang directly, bypassing the southern part of Gyeongju.

Due to the size of the incursion, Wu Wei Zhong and Luo Shang Zhi were reluctant to engage the Japanese in open battle and opted for staying on the defensive. However, Joseon defence in Gyeongju collapsed at the sight of the Japanese, and Korean commanders such as Go Eon-baek (고언백 or 高彥伯) and Hong Gye-nam (홍계남 or 洪季男) fled to Gyeongsang Province to seek help from Liu Ting (劉綎) directly . As the highest ranking commander of Ming army staying in Korea, Liu Ting ordered Ming garrison at Gyeongju to intervene, and the Zhejiang commander had no choice but to obey.

Unfortunately, the incident was forcibly suppressed by dove faction within Ming court to avoid jeopardising the peace talk and prevent the lie that Japanese invaders had already withdrawn from Korea from being exposed. Wu Wei Zhong was thus falsely charged with causing troubles with Korean refugees and was relieved of duty.

3) Siege of Ulsan

3.1) Assault on Ulsan Fortress Complex on Day 2

Date: January 30, 1598

Commander: Chen Yin (陳寅), Mao Guo Qi (茅國器)

Strength: Though the total strength of Ming Left Division was 13,006, the number of infantry was unknown.

Summary: A detachment led by Chen Yin broke through the multi-layered palisades at the northwest corner of Ulsan Fortress Complex and overcame the defence of Ōta Kazuyoshi (太田一吉) and Shishido Mototsugu (宍戸元続), forcing both to retreat into Dosan Fortress.

Meanwhile, Mao Guo Qi also rapidly captured Asano Yoshinaga's camp, Bangujeong Fort and Seobudongseong,

3.2) Desperate assault on Japanese encampment at the southern bank of Taehwa River

Date: February 9, 1598

Commander:  Zu Cheng Xun

Strength: Unknown number of Ming cavalry, supported by a unknown number of Zhejiang infantry detached from Wu Wei Zhong's regiment.

Summary: Zu Cheng Xun's detachment attacked uphill into the camp of Japanese reinforcement that came to relief the siege of Ulsan, and fought Mōri Hidemoto (毛利秀元) to a standstill for a time but was eventually defeated. Zu Cheng Xun and Ming cavalry forcibly barreled through Japanese camp and headed south towards Seosaengpo Fortress, whereas Zhejiang infantry retreated north and crossed Taehwa River under heavy fire, losing more than 200 troops.

Context: Due to the sudden arrival of Japanese reinforcement by both land and water, Zu Cheng Xun's detachment was effectively being trapped between Japanese encampment to his south and Taehwa River to his north, and effectively abandoned when Ming army retreated from the siege. Unknowingly, Zu Cheng Xun's action delayed the river crossing for the Japanese relief force, buying more time for the rest of Ming army to retreat.

4) Post-Ulsan Skirmishes

Date: Late August~early September, 1598

Commander: Dong Yi Yuan (董一元)

Strength: Several hundred infantry

Summary: The small-scale raids conducted by Shimazu Yoshihiro (島津義弘), previously limited to Gyeongsang Province, began to spread to Chungcheong-Jeolla border. After Joseon commander Baeg Yeong-nam (배경남 or 裴敬男) was defeated by the Japanese at Muju and Geumsan, he sent an alert to Dong Yi Yuan in Jeongju, who immediately dispatched several hundred Ming infantry to assist their Joseon counterpart, and together they defeated Shimazu Yoshihiro's raiding party, beheading 20.

Note: Since Dong Yi Yuan was a high-ranking commander leading a large Ming army, the exact make-up of the Ming infantry dispatch was unclear, although they were more likely than not Zhejiang infantry.

5) Siege of Sacheon

Date: November 11, 1598

Commander: Probably Mao Guo Qi

Strength: Unknown

Summary: Due to an unexpected gunpowder accident, Ming army besieging Sacheon fortress fell into disarray. Seizing the golden opportunity, most of the Japanese army poured out of the fortress in pursuit of the routing Ming army. Unexpectedly, a contingent of "red-armoured Ming infantry" under Mao Guo Qi, instead attempted to attack into the now-defenceless fortress (they were simply described as "staying behind and fight to the death" in Chinese and Korean records). Quickly noticing the vulnerability, Shimazu Tadanaga (島津忠長) dispatched three hundred soldiers to resist Ming assault, and was soon joined by several other Japanese commanders, but they were unable to stand against Mao Guo Qi's ferocity. As they were about to be killed, Shimazu Yoshihiro personally dispatched several hundred soldiers to reinforce his subordinates, while Terayama Hisakane (寺山久兼) and Niiro Hisamoto (新納久元) also sallied out of the fortress to Mao Guo Qi's rear and unloaded their matchlock guns on him, finally defeating the Ming contingent and forcing Mao Guo Qi to retreat.

The unswerving determination of Zhejiang infantry (as well as rearguard actions of others) turned what was supposed to be a one-sided massacre of a broken army into a grim struggle, and Shimazu Yoshihiro paid dearly for the victory, losing nearly 3,000 troops in exchange for killing 7~8,000 of Ming army's. After the siege, three to four hundred Ming troops were captured by the Japanese. These prisoners of war were forcibly shaved into Japanese hairstyle before being shipped back to Japan. However, captured Ming troops from Mao Guo Qi's contingent were allowed to keep their Chinese hairstyle out of respect of their combat prowess.

Analysis

As shown in the short list above, Zhejiang infantry weren't the most active participants of Imjin War due to their small numbers, and missed several key battles such as Battle of Byeokjegwan and Battle of Jiksan. Although they did clash with the Japanese on some occasions, most of these were part of a larger military action and sieges, so there is insufficient data to make any judgement on Zhejiang infantry's capabilities on their own.

Still, from what little clashes that are shown here, Zhejiang infantry weren't doing too great, although this was mostly due to factors outside their control. A notable study case is Battle of Angang, of which Zhejiang infantry were essentially thrusted into a situation where they were not only outnumbered but blind (due to the collapse of Joseon defence and with it intelligence gathering), to say nothing of Wu Wei Zhong's contingent being comprised of inexperienced greenhorns recruited just before Imjin War. Thus, it is unsurprising that they walked into an ambush and fell to panic easily.