The Battle of Nagashino, fought in 1575 in Mikawa Province, Japan, is a significant event in Japanese military history. The allied forces of Oda Nobunaga and Tokugawa Ieyasu, numbering 38,000, clashed with Takeda Katsuyori’s 15,000 troops. This battle, which marked a decisive victory for Nobunaga and Ieyasu, significantly aided Nobunaga's ambitions of unifying Japan.

In recent historical discourse, the battle is increasingly referred to as the Battle of Nagashino and Shitaragahara, highlighting the siege of Nagashino Castle and the subsequent battle at Shitaragahara, roughly 4 km west of the castle. This naming underscores the geographical breadth of the conflict.

Regarded as a pivotal shift in Japanese warfare, the Battle of Nagashino is often noted as Japan's first "modern" battle, particularly for Nobunaga's effective use of matchlock firearms, or tanegashima, against Takeda's cavalry. This battle showcased the tactical deployment of arquebusiers, who were organized to fire in successive volleys, a method that significantly halted the effectiveness of the cavalry charge traditionally favored by samurai.

Traditionally, the victory was attributed to strategic innovations such as the use of stockades to block cavalry charges and the organized, rotating fire of arquebusiers. However, recent scholarship suggests there may be additional factors that contributed to the outcome. Despite the ongoing debate over the precise reasons for the Takeda defeat, the impact of matchlock guns, including their role in the death of the notable Takeda general Yamagata Masakage, is well acknowledged. This battle not only exemplifies the shift from classical samurai combat to more contemporary warfare techniques but also marks a significant moment in the power dynamics of the period, consolidating Nobunaga’s path toward the unification of Japan.