Ryūzōji Takanobu was attacking a number of independent clans close to his territories.

When the army was reorganized and commanded by the able Shimazu Iehisa, younger brother of Yoshihisa, the allies put Shimabara under siege and Takanobu marched to relieve the castle with his main army.

On May 3 the Shimazu-Arima army entrenched on a hill in front of Shimabara and received the attack of the Ryūzōji who were well armed with muskets, including high calibre ones.

[4] They were harassed by the Arima with large caliber arquebuses mounted on boats.

The columns were defeated when the Shimazu enticed the Ryūzōji into a false retreat, Harunobu attacked the enemy's main force, and Shimazu retainer, Kawakami Tadakata, allowing a flying column of samurai to take Ryūzōji Takanobu's head.