Siege of Kajiki

The Siege of Kajiki was fought in 1549 the Shimazu clan besieged the castle of Kajiki in what is now Kagoshima prefecture, Japan. The siege succeeded and the castle was taken. The siege is notable for the first time "Portuguese derived" arquebuses were used in battle in Japan.
Shimazu Takahisa attacked the castle of Kajiki in Ōsumi Province, in southern Kyushu. Ijuin Tadaaki, a Shimazu vassal, used a gun provided by Tanegashima Tokitaka. Shimazu Takahisa earned the distinction of being the first Daimyō to use European firearms in battle.
Over the next few years, Shimazu Takahisa continued to expand Shimazu territory on the island of Kyushu.
References.
Sources
↑ Samurai Commanders 1, Stgephen Turnbull pg.49
↑ Samurai Sourcebook, Stephen Turnbull pg.78
↑ Samurai Commanders 1, Stephen Turnbull pg.49