The two battles of Kizugawaguchi (lit. mouth of the Kizu River) were fought during Oda Nobunaga's attempted sieges of the Ishiyama Honganji in Osaka. The Honganji was the primary fortress of the Ikko-ikki, mobs of warrior monks, priests, and farmers who opposed Oda's rule. He ordered one of his admirals, Kuki Yoshitaka, to organize a blockade against the fleets of the Ikki's allies, who sought to supply the fortress and break the siege. Many of the ruling families of the neighboring provinces opposed Oda, chief among them the Mori clan.

The First Battle

In the first battle, in 1576, the Mori defeated Kuki Yoshitaka's fleet, breaking the blockade and supplying the fortress. Both sides fought with firearms, a rather new development in Japanese warfare; but Mori's experience and knowledge of naval tactics was ultimately the deciding factor.

The Second Battle

Two years later, the Ishiyama Honganji was still under siege, and Oda's fleet, commanded once again by Kuki Yoshitaka, made another attempt to break the Mori supply lines. Going against convention, Yoshitaka fought with six very large oo-adakebune ships, rather than a combination of small (kobaya), medium (sekibune), and large (adakebune) craft. Normally, adakebune were essentially wooden floating fortresses, covered in gun & bow emplacements. According to some accounts, it may be believed that these six were the first ironclads, and were built such that guns could not penetrate them. However, rather than true iron clads, made primarily or entirely of metal, these craft probably simply had limited iron plating in key locations.

Several Mori vessels were burned and sunk, and Oda's fleet ultimately achieved victory. The supply lines were broken, and the Honganji fell soon afterwards. However, during this battle an interesting flaw was discovered in the oo-adakebune design. As Mori samurai rushed to board the large ship, all the defending warrior ran to that side of the deck, to defend themselves, and the entire ship fell over as its center of gravity shifted.

Yoshitaka went on to defeat the Mori once more the following year.

References

• Turnbull, Stephen (1998). 'The Samurai Sourcebook'. London: Cassell & Co.