Siege of Tottori Castle by the Amago Revival Army

尼子再興軍による鳥取城の戦い

Yamanaka Yukimori

Inaba Province

Takeda Takanobu

Date:  Eighth and ninth months of Tenshō 1 (1573)

Location:  In and around Tottori Castle in Inaba Province

Synopsis:  After the Amago revival army led by Yamanaka Yukimori established a foothold in Inaba Province and occupied Koshikiyama Castle, Takeda Takanobu, the lord of Tottori Castle, led a contingent of mounted soldiers on a failed assault against the Amago, after which he fled to his base at Tottori Castle.  With momentum from the victory, Yukimori devised a two-part plan to flush the Takeda out of the foothills below Tottori Castle and then to capture the castle with a rear assault, dealing a decisive blow to the Inaba-Takeda clan.

Commanders:  Yamanaka Yukimori, Yamana Toyokuni

Forces:  Approximately 1,000

Losses:  Unknown

Commanders:  Takeda Takanobu

Forces:  Approximately 5,000

Losses:  Approximately 200

The Siege of Tottori Castle by the Amago Revival Army occurred during the eighth and ninth months of Tenshō 1 (1573).  The battle was waged between the Amago Revival Army led by Yamanaka Yukimori and Takeda forces led by Takeda Takanobu, a kokujin in Inaba Province allied with the Mōri clan.  As an outcome of the conflict, the Inaba-Takeda lost their base at Tottori Castle and fell into ruin.

Prelude

From the third to fourth months of Genki 3 (1572), Yamanaka Yukimori, the leader of the Amago revival army, was incarcerated by the Mōri army at Odaka Castle in Inaba Province after failing during the First Campaign to Revive the Amago Clan waged by the remnants of the Amago clan against the Mōri in Izumo Province.  Yukimori, however, managed to escape, going underground in Tajima Province to plan another attempt to revive the Amago clan, summoning former retainers of the Amago with the aim of invading Izumo again.

Early in 1573, the Amago revival army led by Yukimori departed Tajima to invade Inaba and captured Kiriyama Castle in the Ōmi District.  Based from this location, the forces engaged in battles across the area, expanding their power through a series of victories.  Yukimori and his army used Inaba as a foothold from which to advance to the west, aiming to recapture Izumo Province.

At this time, Inaba was governed by Takeda Takanobu, the lord of Tottori Castle.  A decade earlier, in 1563, Takanobu prevailed in battle against the former lord of Inaba, Yamana Toyokazu, a sengoku daimyō and the military governor of Inaba.  Through an alliance with the Mōri clan, Takanobu had since asserted his authority across the province.

After expanding their influence to the west, Yamanaka Yukimori and his army moved their base to Koshikiyama Castle located near Takanobu’s base at Tottori Castle.  Upon learning of these developments, Takanobu committed to the elimination of Yukimori and the Amago revival army.  On 8/1 of Genki 3 (1573), Takanobu led a contingent of 500 mounted soldiers from Tottori Castle and marched toward the base of the Amago revival army at Koshikiyama Castle.  The ensuing clash that resulted in his defeat is known as the Collapse on Tanomo in Tottori.

Following their victory, the Amago revival army allied with Yamana Toyokuni.  Toyokuni was the younger brother of Yamana Toyokazu, the former military governor of Inaba earlier ousted by Takanobu.  Yukimori then decided to eliminate Takanobu.

Later in the same month after having successfully defended Koshikiyama Castle, Yukimori led a contingent of approximately 1,000 troops from the Amago revival army on a march to confront Takanobu who was holed-up at Tottori Castle.

Course of events

In response to the advance of the Amago revival army, the Takeda army led by Takanobu decided upon a defensive strategy taking advantage of the natural terrain to protect Tottori Castle.  The Amago revival army adopted a strategy to take the castle by force.

Tottori Castle was a stronghold built atop Mount Kyūshō at a height of 263 meters.  The design took advantage of the steep incline as a means of protection.  The Amago revival army could not defeat the Takeda by fighting their way up the mountain.  As a result, soldiers on both sides shot arrows and fired arquebuses at one another among the foothills over a period of days.

Aware that the assault had stalled, Yukimori devised a two-phase strategy to break the stalemate.  In the first phase, he aimed to flush the Takeda forces out of the foothills.  The second phase of the plan called for the use of the main battalion as a decoy while another battalion assaulted the castle from behind.

To begin, Yukimori had troops launch incessant attacks from below, drawing the attention of the Takeda forces.  Meanwhile, he sent a portion of the troops on a circuitous route through the town below the castle to prepare for an attack from a direction unanticipated by the Takeda.  While the Takeda forces focused on the soldiers attacking from below, the Amago forces who came from the circuitous route attacked from another side, causing the Takeda to abandon their positions in the foothills.

After relinquishing the foothills to the Amago, the Takeda forces set-up an encampment in the inner citadel of the castle while positioning other troops in various locations in and around the castle to strengthen their defenses to thwart a continued assault by the Amago.

Having determined that an ordinary frontal assault on the castle would not likely succeed, Yukimori considered alternative strategies to topple Tottori Castle through a separate route.  After surveying the surrounding terrain, Yukimori discovered that if he proceeded along a ridge line nearby, he could approach the castle from the rear side.

Eyeing this new opening from which to attack the castle, Yukimori divided his troops into two battalions, ordering the main battalion to commence a frontal assault as a decoy while Yukimori led the other battalion on the route leading to the rear of the castle to launch a surprise attack on the inner citadel.

Last stand by the Takeda at Togami fortress

Owing to the attacks by the Amago, the inner citadel appeared vulnerable to being breached, so the Takeda forces abandoned their positions throughout the castle and gathered at the Togami fortress on a nearby mountaintop from which to mount their defense.  After succeeding in their surprise attack, the Amago forces converged with the battalion that had pressed the attack from the foothills.  These combined units, however, could not overcome fierce resistance by the Takeda forces at Togami fortress.  The Amago forces suspended their attack, withdrawing to the area below the castle.  However, as the Amago forces continued to maintain the siege and pressure the defenders, successive members of the Takeda army began to flee or surrender.  At the end of the ninth month, Takanobu determined that it was futile to continue to fight so he vacated the castle and surrendered.  Upon his surrender, Takanobu tendered his daughter as a hostage to the Amago revival army, while Takanobu himself withdrew to join his younger brother, Takeda Matasaburō, who was holed-up at Hiyodorio Castle.

Consequences

After the battle, Yamana Toyokuni entered Tottori Castle while Yukimori and the Amago revival army entered Kisaichi Castle to serve as their base of operations.

In the next stage of their quest to restore the clan to power, the Amago revival army fought in battles across Inaba Province.  Over the course of ten days, the Amago forces attacked fifteen castles and expanded their power.  The Amago attained control of eastern Inaba while their army increased to over 3,000 troops, creating a foothold from which to further pursue their objectives.

Meanwhile, in the wake of their defeat, the Inaba-Takeda clan fell into decline and, in 1578, was extinguished.