Infantry formations of the Imjin War — Part 1

Zhejiang infantry formation

『遂命諸技, 一時呈技, 隊長在前, 橙牌居次, 砲手又居次, 筤筅、長搶、三枝搶, 又次次居之, 迭相進退, 左旋右抽, 各臻其妙。』

"(He) then ordered various branches to perform (their) skills together, captain at the front, (rattan) shields formed the next rank, gunners formed the rank after next, and Lang Xian, pikes, tridents formed subsequent ranks. Then (they) arrayed in intervals (and) advanced and retreated by turn, spun left and drawn right, each had its own ingeniousness."

— Korean description of Ming infantry formation under Chen Yin (陳寅) during a military demonstration.

『南兵每隊原有銅鍋外，每名椰瓢一箇，每隊斧二把，鎬頭一把。除銃兵牌手原有腰刀外，其筅、鎗、鎲手各要快利腰刀一把，不拘一式。狼筅鎲兵各帶火箭十枝。』

“Beside the copper pot originally given to every Southern troop squad, every (soldier) (should be given) a coconut ladle, every squad (should be given) two axes (and) one pickaxe. Beside the swords originally owned by gunners and shieldbearers, every other Lang Xian, pike, and Tang Pa troop should be given a sharp sword, irrespective of the types (of swords). Every Lang Xian and Tang Pa troop (should) carry ten rockets.”

— Excerpt of Jing Lue Fu Guo Yao Bian (《經略復國要編》), detailing various equipment provided to Ming Southern troops during the first invasion.

Conjectured Imjin War-era Ming Southern infantry formation. This image is cropped, edited and pieced together from various Ming military treatises and training manuals by myself.

Essentially the Imjin War-era iteration of the famous Mandarin Duck Formation, this infantry squad consisted of a captain, two rattan shieldmen, two arquebusiers, two Lang Xian (狼筅), two pikemen, and two Tang Pa (鎲鈀) troops, all armed with swords as secondary weapons. 

With 6 out of 10 troops carrying defensive equipment (two rattan shields, two Lang Xian and two Tang Pa), 6 out of 10 troops armed with ranged weapons (Lang Xian and Tang Pa troops also doubled as rocket troops, in addition to two arquebusiers in the squad), and entire squad capable of fending for themselves in close combat, Zhejiang infantry formation was well-balanced and versatile, able to perform well under a variety of scenarios. However, the formation itself appears to be downgraded from earlier version used by Qi Ji Guang himself, as dedicated arquebusier squads seem to be dissolved and merged into existing infantry squad structure, severely reducing the firepower they could bring.

Japanese battle formation

『則其法, 負旗者居前, 持鳥銃者次之, 持槍劍者又次之,整齊成列, 而左右又巧設奇兵。 每於臨戰之時, 負旗者擺列於左右, 而持銃者放砲, 持槍劍者, 乘氣勢而突進, 左右擺列, 負旗之軍, 又繞出兩邊, 與左右伏兵, 圍繞敵後。酣戰罷散時, 又多置伏兵于左右, 而鳥銃劍槍, 各爲一隊, 散伏草間, 如鳥獸之隱伏, 挑戰之時, 則必以小兵誘引, 俟其陷於伏兵處, 鱗次起戰。』

As for their method, standard bearers formed the front rank, those armed with arquebuses formed the next rank, those armed with spears and swords formed the ranks after the next, (the formation is) neat and orderly. (And they) cleverly deployed unorthodox troops at left and right (flanks). During battle, standard bearers arrayed to left and right (flanks), arquebusiers fired their guns, those armed with spears and swords took the momentum and charge. (At) left and right flanks, standard bearers moved out to left and right (flanks) to encircle the enemy together with ambushers. When (the formation) disengage and disperse during the heat of battle, (they) once again placed many ambushers at left and right (flanks), while arquebusiers and those armed with swords and spears formed their own groups and dispersed to hide among the grass like hiding birds and animals. When (they) provoke a battle, (they) always used a few troops as bait. When (the enemy) fell to the ambush, (they) rose and engaged one after another.

— Yeo Yeo-moon (여여문 or 呂汝文), a Japanese defector, explaining Japanese battle tactics to the Koreans.

This Imjin War-era Japanese battle formation consisted of standard bearers at the foremost rank, arquebusiers positioned behind them, followed by spearmen and swordsmen. In addition, ambushers with unspecified armaments were positioned at both flanks. While neither the number of ranks, nor number of troops was specified, the formation most likely operated at Sonae (備) level, or around 300-800 troops.

Despite sharing a few similarities with its Chinese counterpart (i.e. both formations roughly followed standard bearer-arquebusier-spearman arrangement), Japanese battle formation was evidently much more aggressive and shock-oriented: Japanese troops carried no defensive equipment whatsoever (other than body armours of a handful of better-equipped troops), only utilised matchlock guns to deliver shock during the opening volley before charging into close combat, and made immediate use of flanking attack, all seeking to overwhelm and crush their opponents as quickly as possible. On top of that, Japanese battle formation also appears to be a lot more fluid than Zhejiang formation, with no hard requirement for individual soldiers to maintain cohesion with their squadmates.

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