A Ten-Year Siege: How Ishiyama Hongan-ji Held Out Against Nobunaga

From 1570 to 1580, for ten years. Ishiyama Hongan-ji kept enduring the siege of Oda Nobunaga.

Among the fronts Nobunaga fought in his life, there is no other opponent who remained unsettled for so long.

Here the actual capacity of the religious armed force of the late Sengoku appears symbolically.

The location of Ishiyama Hongan-ji — the ground of the modern Ōsaka Castle — was a water-castle fortress at the northern edge of the Uemachi plateau, with the Yodo River to the east, the Inland Sea to the west, and marshland all around.

A siege from the land was easy, but complete interruption of supply from the waterways was difficult.

This geographical condition was the physical foundation that sustained the ten years of siege.

Toyotomi Hideyoshi's later choice to build Ōsaka Castle on this ground rested on the same evaluation of the strategic advantage of the terrain.

The lifeline of Ishiyama Hongan-ji was supply of materials through the Inland Sea.

The Chūgoku-region daimyō Mōri Terumoto backed Hongan-ji as an anti-Nobunaga force, and the Mōri navy centered on the Murakami navy secured the supply route to Ishiyama.

At the First Battle of Kizugawaguchi in July 1576, the Mōri navy defeated the Oda navy and succeeded in supplying Ishiyama.

Nobunaga had Kuki Yoshitaka build ironclad ships (huge vessels sheathed in iron plate), and at the Second Battle of Kizugawaguchi in November 1578 finally defeated the Mōri navy and cut off the supply.

The Ishiyama War was not a war of Ishiyama Hongan-ji alone but a broad war moving in concert with the Ikkō-ikki of the provinces.

The Ise Nagashima (1570-1574), Echizen (1573-1575), and Kaga (subdued by Nobunaga in 1580) Ikkō-ikki each independently tied up Nobunaga's fronts and dispersed pressure on Hongan-ji.

Kennyo took contact with the adherent leaders of the various regions by letter and coordinated strategy.

A rare case in which the network of a religious organization functioned as a military alliance.

In 1580 (Tenshō 8), peace was concluded by imperial edict of Emperor Ōgimachi. Nobunaga's direct military reduction of Ishiyama Hongan-ji did not succeed to the end.

Kennyo, complying with the imperial edict, withdrew from Ishiyama and moved to Sagimori in Kii Province.

The termination of the ten-year war took a form in which victory and defeat were not decided by force — a political settlement mediated by the authority of the court.

This fact symbolizes the exceptional character of the Ishiyama War.