Jinshin War vs Iwai Rebellion

Ōama began the rebellion with a small force and expanded it by integrating local clans and adapting to terrain, flexibly overcoming guerrilla-style resistance. Ōmi adhered to a rigid defensive doctrine; lack of flexibility in the command structure prevented rapid adaptation to defeats and led to serial collapse.

The Yamato army followed a standard punitive expedition doctrine. Iwai initially established a static defense and naval blockade but failed to develop an alternative strategy in the face of Yamato's determined advance.

Battle of Annihilation

Battle of Annihilation

Ōama correctly identified the strategic center of gravity by first seizing critical passes (Fuwa), consolidating eastern clan support, and then gradually dismantling Ōmi resistance, rather than launching a concentrated assault on the capital immediately. Ōmi concentrated forces on capital defense, a passive approach doomed once supply lines were cut.

Mononobe no Arakabi successfully applied the Center of Gravity principle by directing the main body of his troops at the Tsukushi region, where Iwai's headquarters were located. Iwai, on the other hand, failed to achieve strategic focus by dispersing his forces to different provinces.

Prince Ōama deceived the Ōmi court by disguising himself as a monk and renouncing his succession rights. He also had his troops wear red markers to simplify friend-or-foe identification in battle and increase enemy confusion. Ōmi failed to develop any deception or counterintelligence, even failing to detect Ōama's spies who posed as defectors.

Silla's bribery and instigation of Iwai against Yamato can be assessed as an indirect military deception. Yamato, instead of a direct military ruse, triumphed through overwhelming force and rapid movement.

Limited firepower in this era meant cavalry and archers served as the primary shock elements. Ōama's forces, especially elite warriors like Kume, exploited individual prowess and cavalry charges to breach Ōmi lines. Ōmi's limited shock troops were ineffective in mountainous terrain, and their infantry-heavy armies proved brittle against rapid cavalry maneuvers.

As weapon technology of the period was limited to swords, spears, and bows, a classic shock effect was limited. However, the cavalry units of the Mononobe clan were used as a tactical shock element against Iwai's infantry lines, causing them to scatter.

The summer campaign faced challenges from river crossings and mountainous terrain, but Ōama's forces, aided by local guides and clan support, turned geographical obstacles into advantages. The Ōmi capital was protected by the natural barrier of the Seta River, but this line was breached by Ōama's rapid assault, nullifying the defenders' positional superiority.

The mountainous and forested terrain of Tsukushi was suitable for Iwai's guerrilla-style resistance. However, the final pitched battle took place in an open field where Yamato's disciplined infantry could leverage its advantage.

Ōama maintained information superiority through loyal informants within the Ōmi court, learning of the plot against him in advance. His opponent Ōtomo remained unaware of Ōama's preparations and was misled by faulty intelligence that rendered their defensive plans ineffective.

Thanks to intelligence from Silla, Iwai was aware of Yamato's military preparations and its route. However, Yamato did not entirely overlook the rebellion preparations; the appointment of Mononobe indicates the court had some knowledge of Iwai's intentions.

Upon leaving Yoshino, Ōama conducted a rapid march to quickly seize vital positions like the Fuwa Barrier, securing interior lines of communication. In contrast, Ōmi forces responded with slow-moving, uncoordinated multiple armies, leading to their dispersal against Ōama's concentrated central force.

The Yamato army could not achieve strategic surprise moving by sea to Kyushu; however, after landing, it sought a decisive outcome by directly targeting Iwai's forces in a rapid interior line maneuver. Iwai attempted to fight on multiple fronts by dispersing his troops, but this dispersion became a weakness against the central force.

Ōama's status as the legal heir infused his army with high morale and legitimacy, while voluntary clan participation created a 'victory culture.' On the Ōmi side, a series of early defeats and betrayals bred distrust and collapse, particularly after the killing of Prince Yamabe and suicides among high commanders, embodying Clausewitzian friction at its peak.

Sanctified by imperial edict, the Yamato soldiers possessed a high sense of legitimacy against the forces of Iwai, who were branded as 'rebels'. Local elements on Iwai's side, on the other hand, suffered a moral collapse due to accusations of being 'foreign collaborators' stemming from the Silla alliance.

Prince Ōama survived by feigning abdication before Tenji and accepting Buddhist priesthood, lulling his enemy into complacency while buying time for a counteroffensive. He maintained a legitimate heir image and passively neutralized rival clans.

Silla succeeded in instigating Iwai to distract Yamato from Korea and create an internal conflict. This diplomacy-based maneuver is an early example of the principle of defeating the enemy without direct combat by wearing him down.