Sieges of Toishi

What Happened

The sieges of Toishi Castle ran from 18 October 1550 to 29 June 1551, a campaign fought in the final years of the Muromachi period (1336–1573) and squarely within the Sengoku period. The attacking force belonged to Takeda Shingen, the warlord of Kai Province, who was then pushing his armies into Shinano Province to the north. Command of the siege was given to Sanada Yukitaka, a retainer whose family name would later become famous in its own right.

The castle's defender was Murakami Yoshikiyo, a local lord who refused to yield. For over eight months his garrison held the fortress against the Takeda assault. The cost was severe: more than 1,000 of Yoshikiyo's men were killed or wounded before the end. In the end, the garrison could not hold, and the castle fell to the Takeda forces.

The name given to the event in Japanese, 砥石崩れ, translates roughly as the "Rout of Toishi." The word 崩れ carries a sense of collapse or disintegration, and it marks this siege as a decisive breaking point rather than a simple capture. The fall of Toishi did not end Murakami Yoshikiyo's resistance in Shinano, but it stripped him of a key stronghold and shifted the balance of the campaign decisively toward Takeda Shingen.

Background

Shinano Province in the mid-sixteenth century was a patchwork of competing warlords, none of whom could claim unchallenged supremacy. Takeda Shingen, based in Kai to the south, saw Shinano as the natural direction for expansion. His strategy was methodical: take one castle, consolidate, then move to the next. Toishi Castle stood in the way of that plan.

Toishi was held by Murakami Yoshikiyo, one of the most capable lords in northern Shinano. He had built a network of alliances and fortifications that made him a formidable obstacle. The Takeda army, under Sanada Yukitaka, arrived at Toishi in October 1550 expecting a campaign, not a walkover. They got one.

The siege dragged through the winter and into the spring of 1551. Murakami's garrison fought with enough tenacity that the Takeda forces could not simply storm the walls. But the defenders were cut off, and attrition worked against them. By the time the castle fell in late June, the garrison had lost over 1,000 men. The surrender was not a negotiated settlement; it was the end of what the defenders could physically endure.

Why It Mattered

The fall of Toishi was a turning point in Takeda Shingen's conquest of Shinano. It removed Murakami Yoshikiyo's strongest defensive position and demonstrated that the Takeda army could sustain a long, grinding siege through a harsh winter. Other lords in the province took notice.

For Murakami Yoshikiyo, the loss was crippling. He retreated and continued to resist, but without Toishi his position deteriorated. The siege also elevated Sanada Yukitaka, whose conduct of the campaign earned him a lasting place in Takeda service. His descendants would go on to become some of the most storied warriors of the Sengoku period.

The event's Japanese name, 砥石崩れ, is used by historians to refer specifically to this siege, and it carries the weight of a rout. It was not merely a castle taken; it was a defence broken. That distinction matters because it shaped how contemporaries and later chroniclers understood the campaign: as a demonstration that the Takeda war machine could outlast any defender.

The Name in Japanese

The Japanese name for this event is 砥石崩れ, read in kana as といしくずれ, and in romaji as Toishi kuzure.

The first kanji is 砥, read here as とい (toi). It means "whetstone" or "to polish." In this word it functions as part of the place name Toishi, and the character itself suggests a stone used for sharpening.

The second kanji is 石, read as いし (ishi). It means "stone" or "rock." Together, 砥石 (toishi) forms the place name Toishi, literally "whetstone rock." The castle took its name from this combination.

The third kanji is 崩, read as くずれ (kuzure). It means "collapse," "crumble," or "fall to pieces." In this context it describes the breaking apart of a defensive position — the rout of the garrison. The same character appears in words like 崩壊 (hōkai, "collapse") and 山崩れ (yamakuzure, "landslide").

So the full name 砥石崩れ breaks down as: 砥 (whetstone) + 石 (stone) + 崩れ (collapse). The literal sense is "the collapse of Toishi," and the historical usage treats it as a proper noun for this specific siege. When a Japanese speaker sees 砥石崩れ, they understand not just a battle but a particular disaster that befell the defenders of Toishi Castle.

Key Figures

Takeda Shingen — The warlord of Kai Province who ordered the siege of Toishi as part of his campaign to conquer Shinano. He did not lead the assault personally but directed the overall strategy from the field.

Sanada Yukitaka — The Takeda retainer who commanded the besieging army at Toishi. His successful conduct of the siege cemented his family's position in Takeda service.

Murakami Yoshikiyo — The lord of Toishi Castle and the defender. He held out for over eight months, losing more than 1,000 men before the castle fell. He survived the siege and continued to resist the Takeda advance afterward.