Yabu’s secret musket-force buildup

Yabu’s secret musket-force buildup is a clandestine effort to make firearms, previously treated as dishonorable novelties, the center of a new military system. After discovering the weapons aboard the ship, Yabu sees a chance to turn an arsenal into political and battlefield power: he plans to train selected Samurai to fire as a unit, support them with cannon, and keep the force hidden while the balance of loyalties remains uncertain. The project’s promise is also its danger. It challenges established ideas of honorable combat, requires time that the political crisis may not allow, and gives Yabu reasons to fear both his enemies and his supposed allies.

Weapons and the Strategic Idea

The buildup begins with the scale of the captured arsenal. Yabu privately calculates that it includes five hundred muskets, abundant gunpowder and shot, twenty cannon, thousands of cannonballs, and crates of fire arrows. He orders the arms taken ashore, repacked in their crates, concealed under nets or sacking, and sent secretly to his castle at Mishima. The commands make secrecy part of the military plan from the outset: the weapons are not simply to be stored, but moved and protected without revealing what Yabu intends to do with them.

The plan runs against the prevailing military culture. Firearms had reached Japan decades earlier, and Japanese workshops had begun producing them soon afterward, but guns remained associated with hunting and novelty. Bows were considered more accurate, while warfare was imagined as ritualized individual combat in which the sword offered the more honorable test. Bushido demanded loyalty and fearlessness in service, but the use of guns was treated as cowardly and contrary to its ideals. Yabu’s private exchange with the imagined objections of his ancestors—what of Bushido?—does not resolve that conflict; it exposes the question his innovation will have to overcome.

Yabu’s answer is organizational rather than merely technological. He imagines five hundred chosen Samurai armed with muskets, trained together as a unit, and placed at the head of twelve thousand conventional troops. Twenty cannon would support them, handled by specially trained crews and used according to a new method. In his view, the guns could decide the coming war precisely because they would be integrated into a coordinated force rather than used as isolated weapons. The ambition is to change how men fight, not just what they carry.

Secrecy, Training, and Safeguards

When Yabu later activates the training scheme, he summons Igurashi, Kasigi Omi, and four chief captains. Igurashi is assigned overall command, while Kasigi Omi is to lead one of the five hundreds. They also plan how to incorporate Toranaga’s men into the units if those men arrive, and how to neutralize them if they prove treacherous. The buildup therefore serves two purposes at once: it prepares a force for battle and gives Yabu a means of managing the danger posed by armed allies inside that force.

Kasigi Omi proposes an additional reserve: three more units of one hundred Samurai, trained secretly on the other side of the peninsula. The reserve would replace losses, provide backup, and protect against a treacherous move by Toranaga. The original five hundred are thus only the visible outline of a larger design. Even the question of who commands Toranaga’s men is treated as a security problem. Yabu says he will appoint five assistant officers, each entrusted with killing the commander if necessary, and assigns the code name Plum Tree to the order to kill that commander and all the outsiders. Igurashi is to select the men personally, and they are not to learn Yabu’s overall strategy prematurely.

The plan’s secrecy also creates political friction. Yabu asks how soon war will begin and is told it could start within the year, perhaps in six months or less. Kasigi Omi argues that the five hundred guns and the extra three hundred could give Yabu decisive power, but only once: an enemy that survived the first battle would learn how the formation worked. In his calculation, that single first victory might give Toranaga total victory. The unit’s advantage depends on surprise, which makes concealment, timing, and control of information as important as the weapons themselves.

The Crisis of Loyalty and Time

Kasigi Omi urges Yabu to tell Toranaga about Nebara Jozen and to open the training plans to him. Yabu resists. If the Council is convened and he is absent, Yabu warns, his clan—and Kasigi Omi with it—could be destroyed. He needs at least two months to train the regiment, yet believes he must support Ishido rather than risk standing against the other lords with an unfinished force. The military project is caught between two clocks: the months required to make the men effective and the days remaining before political decisions may become irreversible.

Kasigi Omi presses the case that Yabu has more time than he thinks before leaving for Osaka, and that Ishido is likely to betray him. He urges Yabu to disclose the plans rather than allow suspicion and delay to destroy the chance of preserving Izu and the Kasigi house. Igurashi objects that Nebara Jozen would report the scheme to Ishido, who might steal it; Kasigi Omi counters that the messenger can be followed and killed at a convenient moment. Their disagreement shows how the secret force has become inseparable from the question of whom Yabu can trust. Every disclosure may help secure an ally, but it may also hand the new method to an opponent.

Nebara Jozen is eventually told the strategy in detail. He recognizes why it had been kept secret and expresses admiration, while asking Naga, Toranaga’s son and the second-in-command, for his view. Naga replies only that his father believes every possibility in war should be considered. His restraint leaves the political meaning of the demonstration unsettled: Toranaga’s representative has witnessed the innovation, but the account does not make him an open advocate of it.

Demonstration and Significance

The first full-scale rehearsal sets five hundred attackers against two thousand defenders in a rocky valley. The attackers arrive as a disorderly mounted mass, each carrying a musket and ammunition, but then dismount and form five disciplined phalanxes. Each formation has four ranks of twenty-five men; three advance while two remain in reserve forty paces behind. At command, the front rank fires together, kneels to reload, and gives way to successive ranks firing over it. The coordinated volleys make the larger defending force appear to be cut down, though the ammunition is blank and the casualties are staged.

The demonstration does not pretend that firearms alone can defeat every form of attack. When the defenders charge with swords and spears, the phalanxes break and flee, prompting Nebara Jozen to believe the attackers are being routed. On command, however, they regroup farther back in a V formation and resume firing. The attack falters and stops. The exercise ends with the men sorting themselves out, collecting weapons, laughing and groaning; some are limping and a few are badly hurt. The practical claim is stark: under actual conditions, the two thousand defenders would have been slaughtered.

The scene converts Yabu’s private theory into something an observer can assess. Its force lies not in a single spectacular weapon but in drilled ranks, timed volleys, reserves, movement, and the ability to reform after a retreat. At the same time, the simulated battle remains a rehearsal rather than proof of success in real combat. Its effectiveness depends on discipline under pressure and on the enemy encountering the formation before learning its method—the very conditions threatened by political exposure and inadequate training time.

Yabu’s buildup therefore marks a collision between military innovation and the inherited code of the Samurai, but it is no simple triumph of technology over tradition. The same force that promises decisive power also deepens Yabu’s distrust: its officers are assigned to guard against treachery, a kill order is hidden inside its command structure, and Kasigi Omi tries to steer its use through a shifting allegiance crisis. The guns may alter the first battle; whether Yabu can keep them secret, finish training, and choose the right political moment remains the larger test.