The Honnoji Temple Incident is a military attack on Honnoji Temple which reveals the fact that Nobunaga has been controlled by Xavier.
After partially processing Nobunaga, Xavier took control of Nobunaga's body and moved to Honnoji Temple in order to hide his existence. He ordered Rance to conquer other Houses and unite JAPAN, which greatly differs from his previous negative strategy. In truth, he was making use of Rance's conquer of other Houses and destroying the calabashes which were used to seal Xavier. After the destruction of the fifth calabash, however, Rance discovered his plot and launched the military attack on Honnoji Temple.
Rance's forces crushed the apostles Seiryuu and Byakko and marched in the temple. Shortly before Rance's arrival, Seigan and Ogawa Kentarou has already begun to challenge Xavier, but they were about to lose to Xavier's power. Rance's appearance shifted the situation and Xavier was greatly weakened under the combined attack from Chaos and Nikkou, the two swords that can deal damage to Dark Lords.
Since Xavier is weakened, Nobunaga once again partially gained control of the body and tried to stop Xavier by further wounding himself. No longer able to fight, Xavier jumped out of the building and fled from the battle.
After this incident, Nobunaga's soul finally perished in his last try to stop Xavier, leaving his body fully controlled by Xavier. The younger sister of Nobunaga, Kouhime, sentenced her brother's death. She succeeded her brother as the leader of Oda House and later became the youngest leader of Japan.
After this battle Seigan believes he isn't strong enough to defeat Xavier and goes for training in the mountains with the rest of the sect. Xavier survives the encounter and leads his forces to conquer JAPAN.