The 10-year war from 1570 to 1580 between Oda Nobunaga and Ishiyama Honganji under Kennyo. Among all Nobunaga's enemies during his unification campaign, Ishiyama Honganji resisted the longest. The fortress temple on Osaka Bay (the site of present-day Osaka Castle) became a mighty stronghold, and with naval supply from the Mori, muskets from the Saika-shu, and the united faith of Honganji followers nationwide, it tormented Nobunaga for a full decade. At the First Battle of Kizugawaguchi in 1576, the combined Mori navy and Saika gunners shattered the Oda fleet. At the Second Battle in 1578, Kuki Yoshitaka's iron-plated warships turned the tide, yet the Honganji held on. The war was finally ended in 1580 by imperial mediation from Emperor Ogimachi, and Kennyo withdrew from Ishiyama. But his eldest son Kyonyo advocated continued resistance and broke with his father — a family rift that became the seed of the later 1602 split of Honganji into eastern and western branches.