The Hongan-ji was the primary fortress of the Ikkō-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.

In the first battle, in 1576, the Mōri navy led by Motoyoshi, son of Murakami Takeyoshi, defeated Kuki Yoshitaka's fleet, breaking the blockade and supplying the fortress.

[1] Both sides fought with firearms, a rather new development in Japanese warfare; but Mōri's experience and knowledge of naval tactics was ultimately the deciding factor.

However, these crafts probably had limited iron plating in key locations rather than true ironclads, made primarily or entirely of metal.