Chapter 83: Military Tactics and Technology from Unification To the Manji War
The evolution of the tactics and weaponry of Japan’s samurai armies in the 16th and 17th centuries was convergent to that of Europe. Both being feudal societies in medieval times with a specialized warrior class, their armies incorporated large numbers of common infantry wielding long spears in pike formations at the dawn of the early modern period. Eventually, these infantry units would increasingly adopt gunpowder weapons, starting with the matchlock and arquebus, as their primary if not sole weapon, reducing the significance of melee weapons like swords and spears as well as that of mounted warriors. These changes would also make European and Japanese armies less feudal and more professional and mass-based. The convergent evolutionary trends in such far-flung regions can be attributed to not only their earlier warrior class feudalism but also the constant state of warfare they were both in in the 16th century in particular, albeit for different reasons. Nevertheless, the military tactics, traditions, and technology of Japan was certainly unique and distinct and would remain so even with slight Western influence.
Infantry
The shift of ashigaru weaponry from melee weapons to range-based gunpowder weapons continued unabated and by 1600, the Japanese realm possessed the most guns in the world. Towards the end of the unification wars, as many as one-fourth of all troops were arquebusiers. After the unification wars, however, 48 years of peace followed which saw the demobilization of the mass armies that defined the late Sengoku period and the confiscation of weapons from the peasantry. Nevertheless, clans continued to train and keep a reserve of ashigaru alongside their samurai retinues. Ironically, the long peace and demobilization would accelerate the switch to arquebuses and matchlocks as they were much easier to train newly levied men with as opposed to swords and spears, which required more long-term skill and training. Another factor that contributed was the fact that Azuchi and the samurai clans consciously chose to increase the share of arquebusiers in response to fighting a technologically advanced enemy in the form of the Spanish and Portuguese. In fact, mass formations of yari ashigaru would see their last usage in the Furuwatari War, particularly by the Hojo and other rebellious clans in the Kanto and Oshu regions who lacked the same consistent interactions with foreign merchants, who mainly operated in western Japan, and their goods, knowledge, and technology. Those formations would afterwards be regarded as obsolete, especially with the knowledge of the state of warfare in Europe. By this time, archers had also completely disappeared from samurai armies, although they maintained their historic prestige and continued to be for ceremonial, martial, and hunting purposes.
Replacing them would be combined arms formations influenced by both contemporary samurai warfare and new European tactics. Infantry lines mixed arquebusiers, yari ashigaru, and blade-wielding samurai in succeeding lines. This formation had begun to emerge in the Iberian-Japanese and Furuwatari Wars but did not displace older formations until the 1640s through the Kanei reforms and the standardization of the newly established regional standing armies. The emergence of combined arms warfare in Japan also saw the final disappearance of standing shields in samurai warfare, already gradually becoming obsolete with the advent of arquebuses. These formations instead would incorporate the line infantry marching tactics of the Franco-Dutch and Swedish armies used in the Imperial Liberties’ War, the Franco-Spanish War, and the Dutch War of Independence. The strength of the new combined arms formations was that they had a high degree of flexibility, being able to quickly engage in melee combat in forested areas or in instances of close confrontation. Their lethality would also be increased by the gradual adoption of more advanced muskets like flintlocks.
17th century drawing of the arquebusier
During the Manji War, Oda Tomoaki would take it a step further and utilize line infantry tactics to their greatest extent, retaining an elite unit of flintlock-equipped musketeers focused on rapid fire tactics. Instead of being supported by yari ashigaru and blade-wielding samurai, these elite units were trained to immediately switch to melee combat if charged using swords and the butts of their muskets. These units, unlike the average musket ashigaru, were mostly made up of middle and high-ranking samurai and were fully armored.
Cavalry
Samurai cavalry would change little in terms of their equipment and tactics through the 16th and 17th centuries. The biggest change was the increased incorporation of the bajouzutsu in combat. During the Sengoku period, samurai cavalry were of three different types: mounted infantry, medium cavalry, and heavy cavalry. The first cavalry type would fade away with the increased importance of ashigaru and mass armies in the home islands. However, they would continue to exist in Bireitō and Luson, where the large swaths of jungle made the use of cavalry-specific tactics less common than in the home islands. Similar to during the Sengoku period, medium cavalry remained more prevalent in western Japan while heavy cavalry was more common in eastern Japan. Medium cavalry, which primarily wielded swords and bajouzutsu and focused on skirmishing and flanking maneuvers, would also predominate in armies in Bireitō and Luson. So-called heavy cavalry, which specialized in frontal charges and always used the spear as the primary weapon rather than their sword or bajouzutsu that they still equipped, would however form the core of the Konoe Cavalry, Azuchi’s elite cavalry force made up of young samurai and nobles. Sakuma Moritora’s elite core of samurai were themselves heavy cavalry, with the Chinjufu shogun himself famously leading cavalry charges.
Depiction of cavalry from the Budou-geijutsu-hidenzue (武道藝術秘傳圖會) manual
Artillery
Unlike Europe, cannons did not see widespread adoption in Japan especially in field battles. This would change somewhat in the 17th century after the development of the Azuchi navy had increased Japanese familiarity with European-style cannons. The Iberian-Japanese and Furuwatari Wars would see the introduction of field guns that would prove crucial for Azuchi’s victories in those two wars. Japanese armies preferred to use smaller guns like demi-culverins rather than the larger culverins and demi-cannons due to the mountainous and forested terrains of the home islands and Luson. They were also easier to use during sieges against castles, although in many cases the terrain made their usage difficult if not impossible. Rather, muzzle-loading hand cannons and breech-loading swivel guns as well as smaller cannon pieces like the saker were most often used against castles and other fortifications during this time. The former two were also used extensively by the besieged. Many castles were perfectly designed to incorporate the strengths of these pieces being that many of them were already designed to maximize the lethality of arquebuses
Bireitō and Luson
Being overseas provinces in the tropics host to large populations of indigenous peoples, samurai tactics and fighting styles in Bireizen and Bireigo on the island of Bireitō as well as Luson diverged from those seen in the home islands to adapt properly in these new lands. Towards the end of the 16th century, the katana (刀) began to replace the longer and more curved tachi (太刀) as the primary sword used when fighting on foot and carried around in civilian everyday functions in the home islands, although the tachi would continue in use among samurai cavalry units and for ceremonial purposes by high-ranking samurai and the nobility. However, the tachi would continue on as the signature melee weapon in the overseas provinces, especially in forested areas and smaller open clearings. This was due to the militaries there relying more on heavy samurai infantry rather than ashigaru masses or cavalry because of the terrain, the nature of the foes they faced, and absence of a native Japanese peasant population. Wakizashis (脇差) were also more heavily utilized in close combat situations as well, as were bajouzutsus and arquebuses.
Tachi of Oda Tadataka, governor of Bireit
ō and commander-in-chief of land forces in the Iberian-Japanese War
Commonly filling the role of the ashigaru were the Chinese colonists in Bireitō and the indigenous Lusonese in the lowlands of Luson, both generally wearing traditional Japanese armor except for the jingasa hat (陣笠). These levies, however, were not as well trained as their Japanese counterparts due to their lower utility and smaller amount of open plains where ashigaru masses were most ideal. By contrast, troops from the Bireitoan aborigines and the Luson highlands were employed more frequently, serving as light skirmishers and archers in their traditional styles. The Bireitoan elite, however, were fully trained in the samurai fighting style and integrated in the Bireitoan military apparatus as such. Additionally, the retinue of the Zheng clan was militarily distinct from everyone else, wearing Ming armor and wielding yao swords and spears although they did use Japanese firearms. These non-Japanese auxiliaries further distinguished the militaries of Bireitō and Luson from that of the home islands.
